capistrano output - failing to install pg gem

deploy.rb

require "bundler/capistrano"

require "rvm/capistrano"
#set :rvm_ruby_string, :local # from https://github.com/wayneeseguin/rvm-capistrano
set :rvm_type, :system # from http://stackoverflow.com/questions/5253153/rvm-error-with-deploying-rails-app-via-capistrano

default_run_options[:shell] = '/bin/bash --login'

set :application, "sneakerology_spree"
set :repository,  "ssh://git@bitbucket.org/bbldigital/sneakerology-ecom.git"

set :scm, :git
ssh_options[:forward_agent] = true
default_run_options[:pty] = true
set :user, "deploy" # To set up deploy user, follow instructions at http://www.capistranorb.com/documentation/getting-started/authentication-and-authorisation/ but if you already have an id_rsa in ~/.ssh, no need to create a new one - use the same one.
set :deploy_to, "/var/www/vhosts/sneakerology.com.au/staging/"
set :use_sudo, false # deploy user will need the right permissions so we don't have to use sudo to create files / folders etc

role :web, "sneakerology.com.au"                          # Your HTTP server, Apache/etc
role :app, "sneakerology.com.au"                          # This may be the same as your `Web` server
role :db,  "sneakerology.com.au", :primary => true # This is where Rails migrations will run

# if you want to clean up old releases on each deploy uncomment this:
set :keep_releases, 3
after "deploy:restart", "deploy:cleanup"
after 'deploy:update_code', 'deploy:migrate'

# if you're still using the script/reaper helper you will need
# these http://github.com/rails/irs_process_scripts

# If you are using Passenger mod_rails uncomment this:
namespace :deploy do
  task :start do ; end
  task :stop do ; end
  task :restart, :roles => :app, :except => { :no_release => true } do
    run "#{try_sudo} touch #{File.join(current_path,'tmp','restart.txt')}"
  end
end

gistfile1.txt

Joshuas-MacBook-Pro:www joshuapaling$ cap deploy:update
    triggering load callbacks
  * 2013-08-12 11:27:38 executing `deploy:update'
 ** transaction: start
  * 2013-08-12 11:27:38 executing `deploy:update_code'
    executing locally: "git ls-remote ssh://git@bitbucket.org/bbldigital/sneakerology-ecom.git HEAD"
    command finished in 6208ms
  * executing "git clone -q ssh://git@bitbucket.org/bbldigital/sneakerology-ecom.git /var/www/vhosts/sneakerology.com.au/staging/releases/20130812012744 && cd /var/www/vhosts/sneakerology.com.au/staging/releases/20130812012744 && git checkout -q -b deploy 4714e3f4827ab50f4ea1dcb4b423b2c2e84d5457 && (echo 4714e3f4827ab50f4ea1dcb4b423b2c2e84d5457 > /var/www/vhosts/sneakerology.com.au/staging/releases/20130812012744/REVISION)"
    servers: ["sneakerology.com.au"]
    [sneakerology.com.au] executing command
    command finished in 4376ms
  * 2013-08-12 11:27:53 executing `deploy:finalize_update'
    triggering before callbacks for `deploy:finalize_update'
  * 2013-08-12 11:27:53 executing `deploy:assets:symlink'
  * executing "rm -rf /var/www/vhosts/sneakerology.com.au/staging/releases/20130812012744/public/assets && mkdir -p /var/www/vhosts/sneakerology.com.au/staging/releases/20130812012744/public && mkdir -p /var/www/vhosts/sneakerology.com.au/staging/shared/assets && ln -s /var/www/vhosts/sneakerology.com.au/staging/shared/assets /var/www/vhosts/sneakerology.com.au/staging/releases/20130812012744/public/assets"
    servers: ["sneakerology.com.au"]
    [sneakerology.com.au] executing command
    command finished in 1803ms
  * 2013-08-12 11:27:55 executing `bundle:install'
  * executing "cd /var/www/vhosts/sneakerology.com.au/staging/releases/20130812012744 && bundle install --gemfile /var/www/vhosts/sneakerology.com.au/staging/releases/20130812012744/Gemfile --path /var/www/vhosts/sneakerology.com.au/staging/shared/bundle --deployment --quiet --without development test"
    servers: ["sneakerology.com.au"]
    [sneakerology.com.au] executing command
 ** [out :: sneakerology.com.au] Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.
 ** [out :: sneakerology.com.au] 
 ** [out :: sneakerology.com.au] /usr/local/rvm/rubies/ruby-1.9.3-p448/bin/ruby extconf.rb
 ** [out :: sneakerology.com.au] checking for pg_config... no
 ** [out :: sneakerology.com.au] No pg_config... trying anyway. If building fails, please try again with
 ** [out :: sneakerology.com.au] --with-pg-config=/path/to/pg_config
 ** [out :: sneakerology.com.au] checking for libpq-fe.h... no
 ** [out :: sneakerology.com.au] Can't find the 'libpq-fe.h header
 ** [out :: sneakerology.com.au] *** extconf.rb failed ***
 ** [out :: sneakerology.com.au] Could not create Makefile due to some reason, probably lack of
 ** [out :: sneakerology.com.au] necessary libraries and/or headers.  Check the mkmf.log file for more
 ** [out :: sneakerology.com.au] details.  You may need configuration options.
 ** [out :: sneakerology.com.au] 
 ** [out :: sneakerology.com.au] Provided configuration options:
 ** [out :: sneakerology.com.au] --with-opt-dir
 ** [out :: sneakerology.com.au] --without-opt-dir
 ** [out :: sneakerology.com.au] --with-opt-include
 ** [out :: sneakerology.com.au] --without-opt-include=${opt-dir}/include
 ** [out :: sneakerology.com.au] --with-opt-lib
 ** [out :: sneakerology.com.au] --without-opt-lib=${opt-dir}/lib
 ** [out :: sneakerology.com.au] --with-make-prog
 ** [out :: sneakerology.com.au] --without-make-prog
 ** [out :: sneakerology.com.au] --srcdir=.
 ** [out :: sneakerology.com.au] --curdir
 ** [out :: sneakerology.com.au] --ruby=/usr/local/rvm/rubies/ruby-1.9.3-p448/bin/ruby
 ** [out :: sneakerology.com.au] --with-pg
 ** [out :: sneakerology.com.au] --without-pg
 ** [out :: sneakerology.com.au] --with-pg-dir
 ** [out :: sneakerology.com.au] --without-pg-dir
 ** [out :: sneakerology.com.au] --with-pg-include
 ** [out :: sneakerology.com.au] --without-pg-include=${pg-dir}/include
 ** [out :: sneakerology.com.au] --with-pg-lib
 ** [out :: sneakerology.com.au] --without-pg-lib=${pg-dir}/lib
 ** [out :: sneakerology.com.au] --with-pg-config
 ** [out :: sneakerology.com.au] --without-pg-config
 ** [out :: sneakerology.com.au] --with-pg_config
 ** [out :: sneakerology.com.au] --without-pg_config
 ** [out :: sneakerology.com.au] 
 ** [out :: sneakerology.com.au] 
 ** [out :: sneakerology.com.au] Gem files will remain installed in /var/www/vhosts/sneakerology.com.au/staging/shared/bundle/ruby/1.9.1/gems/pg-0.15.1 for inspection.
 ** [out :: sneakerology.com.au] Results logged to /var/www/vhosts/sneakerology.com.au/staging/shared/bundle/ruby/1.9.1/gems/pg-0.15.1/ext/gem_make.out
 ** [out :: sneakerology.com.au] An error occurred while installing pg (0.15.1), and Bundler cannot continue.
 ** [out :: sneakerology.com.au] Make sure that `gem install pg -v '0.15.1'` succeeds before bundling.
    command finished in 70663ms
*** [deploy:update_code] rolling back
  * executing "rm -rf /var/www/vhosts/sneakerology.com.au/staging/releases/20130812012744; true"
    servers: ["sneakerology.com.au"]
    [sneakerology.com.au] executing command
    command finished in 1713ms
failed: "rvm_path=/usr/local/rvm /usr/local/rvm/bin/rvm-shell 'default' -c 'cd /var/www/vhosts/sneakerology.com.au/staging/releases/20130812012744 && bundle install --gemfile /var/www/vhosts/sneakerology.com.au/staging/releases/20130812012744/Gemfile --path /var/www/vhosts/sneakerology.com.au/staging/shared/bundle --deployment --quiet --without development test'" on sneakerology.com.au