Support for projects at various directory levels in workspace

This pull request goes with the companion one for bnd: https://github.com/bndtools/bnd/pull/405
My team is has been using these changes for over a year now. Unfortunately we've been stuck on an older version of bndtools, however I'm in the process of upgrading us to 2.2.0.

With these changes, you can have bnd based projects at any directory level in your bnd workspace.