/brz/remove-bazaar

Todo
====

- revision inventory synthesis, a-la bzr-hg.
- file content data access.
- native cloning - so bzr branch fromgit togit works.
- conversion pulling - so bzr init; bzr pull fromgit works.
- remove the dependency on stgit - the amount of code reuse is trivial compared
  to the installation overhead of a dependency. 
- possibly generate a factored out generic 'git' python module if our native
  bindings become big enough.