Helper project for testing with PAX-Exam/JUnit

Helper project for testing with Pax-Exam/JUnit. Consists of two parts:

- list of Pax-Exam related dependencies declared in the pom (runtime
  scope), so that they can easily be imported and don't have to be
  repeated for each project
- convenience functions for configuring Pax-Exam:
  - list of bundles needed for XProcSpec testing
  - list of bundles needed for XSpec testing
  - minimal list of Pipeline framework bundles needed for
    XProcSpec/XSpec testing
  - ...

blocked on #5