This changes the mock backend from RxMocks to Mockito.
The logic present in RxMocks to deal with event syncronisation has been ported to this repo under the class RxMocks.

This change allows us to mock non Interface repositories. It also allows us to use verify logic on the mocked repo to do some UI unit testing on cases where UI modifies data through the repository.

The usage hasn't changed much, mainly the mocks are now created using mockito and RxPresso is now created through an init method.