Adds Bazaar (bzr) SCM tool support. It is implemented simply by invoking external application (like the cvs support too). However, Bazaar diffs do not contain revision numbers but timestamps. The solution is to find the corresponding revision number in parse_diff_revision function using bzr log.

This is my very first piece of Python code. I submit this, since there might be some other Bazaar users who are willing to participate or help. All comments are welcome. :) 

Tested with simple Bazaar repository. I invite all Bazaar users to help testing this.