/usr/local/rvm/rubies/ruby-1.9.2-p180/lib/ruby/site_ruby/1.9.1/rubygems/dependency.rb:247:in `to_specs': Could not find unicorn (>= 0) amongst [minitest-1.6.0, rake-0.8.7, rdoc-2.5.8] (Gem::LoadError)
    from /usr/local/rvm/rubies/ruby-1.9.2-p180/lib/ruby/site_ruby/1.9.1/rubygems/dependency.rb:256:in `to_spec'
    from /usr/local/rvm/rubies/ruby-1.9.2-p180/lib/ruby/site_ruby/1.9.1/rubygems.rb:1230:in `gem'
    from /usr/local/rvm/gems/ruby-1.9.2-p180/bin/unicorn_rails:18:in `<main>'