Multileveldirs 2.2.0 rebase

This is a rebasing of the same functionality I previously "pull requested". There have been a couple bug fixes and a small junit test added, but the basic concept is still the same. It's been working for my team for over a year now.

I implemented support for BND to handle bundle projects at various levels in a workspace.

To use, add the "-projectsearch" BND directive to cnf/build.bnd or cnf/ext/*.bnd

An example:
   -projectsearch: .;depth=1,dir;depth=1
This tells BND to search for projects under the workspace and any projects under /dir. But only search one level down into each. The depth parameter defaults to 0, which means that it doesn't recurse down into another level of directories.
If -projectsearch is not specified, the default is the old behavior, which should be equivalent to ".;depth=1"