buildbotService: based on Restangular

buildbotService is a typical restangular object, but adds methods
to automatically update scope based on 'sse' events

Add unit tests:
 - EventSourceMock simulates events
 - buildbotServiceMock simulates the whole buildbotservice, with help
   from dataspec json info. This will be used to easily test controllers

add restangular and lodash deps.