Fix: Resolving steps of referenced jars

This code fixes #5, handling the case when steps are provided in jars from dependencies, where annotations are identified with the full qualified name.

Code changes in a gist:
* Extracted step candidate calculation into dedicated MethodToStepCandidateReducer class
* Added unit tests for this class, including error case
* Reasonable code cleanup; Further refactoring could consider extracting the handling of specific annotations into dedicated strategies...

Note: This merge also includes the code from merge request #8