Added basic functionality to search for github users using the github api.

Nothing fancy here.  Just hit the uri and spit out the result.  I added some basic testing so that this would be easier to extend.  For feature tests I utilized vcr purely for the speed increases.  However, I chose not to use vcr for the model tests.  We still want to hit the api directly, just to confirm that they are still returning what we expect them to and the model seemed like the best place for that in this scenario.