uninitialized constant Bundler (NameError)

gem --version

developer@ubuntu:~/Workspace/supermarket$ gem --version
2.1.7

Gemfile

source 'http://rubygems.org/'

gem 'unicorn'

# group :app do
gem 'ruby-odbc', '0.99995'
gem 'sinatra'
#gem "sinatra-activerecord"
gem 'sinatra-contrib'
gem 'activerecord', '3.2.13'
gem 'activerecord-sqlserver-adapter', '3.2.10'
gem 'tiny_tds'
gem 'composite_primary_keys'
gem 'roo'
gem 'nokogiri'
gem 'axlsx'
gem 'capistrano'
gem 'rvm-capistrano'
gem 'coderay', '1.0.9'

gem 'pry'
# end

group :test do
  gem 'rspec'
  gem 'rack-test'
  gem 'factory_girl'
  gem 'simplecov', :require => false
end

Gemfile.lock

GEM
  remote: http://rubygems.org/
  specs:
    activemodel (3.2.13)
      activesupport (= 3.2.13)
      builder (~> 3.0.0)
    activerecord (3.2.13)
      activemodel (= 3.2.13)
      activesupport (= 3.2.13)
      arel (~> 3.0.2)
      tzinfo (~> 0.3.29)
    activerecord-sqlserver-adapter (3.2.10)
      activerecord (~> 3.2.0)
    activesupport (3.2.13)
      i18n (= 0.6.1)
      multi_json (~> 1.0)
    arel (3.0.2)
    axlsx (2.0.1)
      htmlentities (~> 4.3.1)
      nokogiri (>= 1.4.1)
      rubyzip (~> 1.0.0)
    backports (3.3.4)
    builder (3.0.4)
    capistrano (2.15.5)
      highline
      net-scp (>= 1.0.0)
      net-sftp (>= 2.0.0)
      net-ssh (>= 2.0.14)
      net-ssh-gateway (>= 1.1.0)
    coderay (1.0.9)
    composite_primary_keys (5.0.13)
      activerecord (~> 3.2.0, >= 3.2.9)
    diff-lcs (1.2.4)
    factory_girl (4.2.0)
      activesupport (>= 3.0.0)
    highline (1.6.19)
    htmlentities (4.3.1)
    i18n (0.6.1)
    kgio (2.8.1)
    method_source (0.8.2)
    mini_portile (0.5.1)
    multi_json (1.8.1)
    net-scp (1.1.2)
      net-ssh (>= 2.6.5)
    net-sftp (2.1.2)
      net-ssh (>= 2.6.5)
    net-ssh (2.7.0)
    net-ssh-gateway (1.2.0)
      net-ssh (>= 2.6.5)
    nokogiri (1.6.0)
      mini_portile (~> 0.5.0)
    pry (0.9.12.2)
      coderay (~> 1.0.5)
      method_source (~> 0.8)
      slop (~> 3.4)
    rack (1.5.2)
    rack-protection (1.5.0)
      rack
    rack-test (0.6.2)
      rack (>= 1.0)
    raindrops (0.12.0)
    roo (1.12.2)
      nokogiri
      rubyzip
      spreadsheet (> 0.6.4)
    rspec (2.14.1)
      rspec-core (~> 2.14.0)
      rspec-expectations (~> 2.14.0)
      rspec-mocks (~> 2.14.0)
    rspec-core (2.14.5)
    rspec-expectations (2.14.3)
      diff-lcs (>= 1.1.3, < 2.0)
    rspec-mocks (2.14.3)
    ruby-odbc (0.99995)
    ruby-ole (1.2.11.7)
    rubyzip (1.0.0)
    rvm-capistrano (1.5.1)
      capistrano (~> 2.15.4)
    simplecov (0.7.1)
      multi_json (~> 1.0)
      simplecov-html (~> 0.7.1)
    simplecov-html (0.7.1)
    sinatra (1.4.3)
      rack (~> 1.4)
      rack-protection (~> 1.4)
      tilt (~> 1.3, >= 1.3.4)
    sinatra-contrib (1.4.1)
      backports (>= 2.0)
      multi_json
      rack-protection
      rack-test
      sinatra (~> 1.4.0)
      tilt (~> 1.3)
    slop (3.4.6)
    spreadsheet (0.9.0)
      ruby-ole (>= 1.0)
    tilt (1.4.1)
    tiny_tds (0.6.1)
    tzinfo (0.3.38)
    unicorn (4.6.3)
      kgio (~> 2.6)
      rack
      raindrops (~> 0.7)

PLATFORMS
  ruby

DEPENDENCIES
  activerecord (= 3.2.13)
  activerecord-sqlserver-adapter (= 3.2.10)
  axlsx
  capistrano
  coderay (= 1.0.9)
  composite_primary_keys
  factory_girl
  nokogiri
  pry
  rack-test
  roo
  rspec
  ruby-odbc (= 0.99995)
  rvm-capistrano
  simplecov
  sinatra
  sinatra-contrib
  tiny_tds
  unicorn

rspec

developer@ubuntu:~/Workspace/supermarket$ rspec 
/home/developer/Workspace/supermarket/spec/spec_helper.rb:8:in `<top (required)>': uninitialized constant Bundler (NameError)
	from /home/developer/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/site_ruby/1.9.1/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /home/developer/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/site_ruby/1.9.1/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /home/developer/Workspace/supermarket/spec/ws_spec.rb:3:in `<top (required)>'
	from /home/developer/.rvm/gems/ruby-1.9.3-p448@supermarket_dev/gems/rspec-core-2.14.1/lib/rspec/core/configuration.rb:896:in `load'
	from /home/developer/.rvm/gems/ruby-1.9.3-p448@supermarket_dev/gems/rspec-core-2.14.1/lib/rspec/core/configuration.rb:896:in `block in load_spec_files'
	from /home/developer/.rvm/gems/ruby-1.9.3-p448@supermarket_dev/gems/rspec-core-2.14.1/lib/rspec/core/configuration.rb:896:in `each'
	from /home/developer/.rvm/gems/ruby-1.9.3-p448@supermarket_dev/gems/rspec-core-2.14.1/lib/rspec/core/configuration.rb:896:in `load_spec_files'
	from /home/developer/.rvm/gems/ruby-1.9.3-p448@supermarket_dev/gems/rspec-core-2.14.1/lib/rspec/core/command_line.rb:22:in `run'
	from /home/developer/.rvm/gems/ruby-1.9.3-p448@supermarket_dev/gems/rspec-core-2.14.1/lib/rspec/core/runner.rb:80:in `run'
	from /home/developer/.rvm/gems/ruby-1.9.3-p448@supermarket_dev/gems/rspec-core-2.14.1/lib/rspec/core/runner.rb:17:in `block in autorun'
Coverage report generated for RSpec to /home/developer/Workspace/supermarket/coverage. 0 / 0 LOC (0.0%) covered.