add travis-ci build status to readme
Merge remote-tracking branch 'upstream/master'

* upstream/master:
  Add aq1018 and akahn as contributors
  Add travis CI buttons
  Bump version now that we have 1.8.7 support back
Added current ruby version and code climate scores to README
Merge pull request #25 from aq1018/master

Added gem version and code climate score images to README