Integrated ruby gem api

Added functionality: A user cannot add a gem that is not in listed in the Ruby Gem API. 

**All tests are green

***BEFORE WE MERGE, PLEASE SEE ISSUES BELOW
I've noticed two bugs: 
1) validates_uniqueness_of :name on the ruby_gem model is validating "Devise" and "devise" as two unique gems
2) the ruby_gem_API_query(params) method on the RubyGemsController can't handle scenarios where the user includes spaces in the gem name