Implement PowerMock annotation engine

[thekingn0thing]

At current moment PowerMock uses either EasyMock or Mockito annotation processing classes to create and inject mocks base on annotation. But to support ability creating mocks for not-mockable types PowerMock uses dirty hacks and internal code of mocking frameworks. to avoid such behaviour and depending on internal API PowerMock has to support it own custom annotation engine that have to support basic feature of frameworks engine or call only public API.

Take into account case with injection for modified classes
#807 (comment)