This is a massive commit which reorganizes the entire project structure
(although it is still monolithic), removes the Build classes, and
switches to Moxie, a smarter Ant build tookit based on the original
Gitblit Build classes.

The Ant build script will likely require additional fine-tuning, but
this is big step forward.

This is an in-progress feature to offer an interface for grouped
repositories.  This may help installations with large numbers of
repositories stay organized.  It also will be part of a future,
more advanced security model.