MockitoAnnotations.initMocks() returns List of all created mocks

* MockitoAnnotations.initMocks( .. ) returns List of all created mocks
* added simple tests for the new feature to InitMocksReturnsMocksTest class

This is a convenience feature that allows you to get a list of all mocks created when calling initMocks, so you can then push these mocks to for example test ApplicationContext in Spring unit tests or do some post processing for all the mocks.