Add git-salt module.

Add an initial communication between CDE and git-nacl port (`git-salt`).

1) This enables a `git-clone` powered by nacl behind a flag.
2) This is still a work in progress, and lot of things may be broken.
3) Some debug logs are left intentionally, will be cleaned in future.

This is copied from somewhere, right?  I think you can do away with the div by attaching the event handlers *before* setting the src.