Minor redesign.

Fix binary packages

- fix Windows package (it could only run on machines that had Python installed)
- OS X package is much smaller, and is now compatibile with Snow Leopard
- add StupidGit context menu item in Windows

First public release.

Features:
- Open existing repository, quick switch between submodules
- History graph and diff viewer
- Index editor (stage / unstage files)
- Commit, set commit author/email
- Switch wizard that can do most of checkout/reset variants
- Merge, resolve conflicts with external tool (meld / WinMerge / DiffMerge)
  or by taking the local/remote version
- Cherry-pick, revert commit