environments files should be inside a folder named deploy.

deploy.rb

require "capistrano_colors"
require "railsless-deploy"

set :default_stage, "dev"
require "capistrano/ext/multistage"

set :use_sudo, false
set :application, "bar"
set :user, "www-data"
set :group, "www-data"
set :scm, :git
set :repository, "git@github.com:foo/#{application}.git"
set :branch, "master"
set :deploy_via, :remote_cache

ssh_options[:forward_agent] = true
default_run_options[:pty] = true

namespace :deploy do
  task :set_deploy_folder do
    set :deploy_to, "/var/www/#{application}_#{stage}"
  end
  task :run_ant do
    run "cd #{release_path} && ant assembly -Dstage=#{stage}"
    #keep just the WebContent folder
    run "cd #{release_path} && ls | grep -v WebContent | xargs rm -fr" 
  end
end

after "deploy:symlink", "deploy:run_ant"
after "deploy:update", "deploy:cleanup"
before "deploy", "deploy:set_deploy_folder"
before "deploy:setup", "deploy:set_deploy_folder"

dev.rb

server 'dev.bar.com', :app, :web, :db, :primary => true

set :db_server, "jdbc:postgresql://devdb.bar.com/dev"
set :db_user, :dev

production.rb

server 'production.bar.com', :app, :web, :db, :primary => true

set :db_server, "jdbc:postgresql://productiondb.bar.com/production"
set :db_user, :production