CYB-253 Backend: Users should not be able to like or dislike their own work?
  * totally blocks a user from liking/disliking their own work, returning 403 Forbidden
  * small refactor of rails_helper.rb to add new matcher (have_return_status)

https://jira.ets.berkeley.edu/jira/browse/CYB-253
Merge pull request #176 from coyote/block_self_likes

CYB-253 Backend: Users should not be able to like/dislike their own work