Add Code Climate test coverage integration

[galbernator]

Add the Code Climate test coverage gem to be able to update test coverage on the README.

[galbernator]

PR #19 adds the gem and also integrates Travis CI. Closing.

[galbernator]

Looks like I jumped the gun on closing this one. Not sure exactly where the hang up is. Will do some more research into it and get back to it.