New Bazaar module

This module for the Bazaar version control software (DVCS) is based on the Git module. It doesn't support multiple branches per directory (shared repositories), but that's less usual on bzr, so I don't think it's a great loss.

I've tested branching (cloning) and pulling new revisions, both to the latest revision (nicknamed `head`) or previous ones, but it wasn't exhaustive. 

The options are the same as for the Git module, but it calls `parent` to the repo being branched from, and it doesn't have a remote name, since as far as I know bzr has no such functionality.