Add mockito support to HK2

I have created a new module that adds the ability to spy on HK2 services using Mockito spies. This module effectively gives users the ability to inject services and their collaborators into test cases and verify service method calls as well as calls to methods of collaborating services.

Please take a look at the test cases and let me know what you think. Note that I am not too keen on the annotation names so feel free to change it as you see fit.