Moved Gemfile to test.gemfile

Otherwise, Heroku deploys assume that this app is a Ruby app instead of
a Node.js app
Modified rake tasks to rely on custom gemfile for tests
Updated README to coincide with new testing functionality

given new gemfile location
Merge pull request #25 from rmm5t/subtract-gemfile

Gemfile tricks Heroku into thinking this is a Ruby app instead of a Node.js app