elaborate project workflow and history policy

outlined the project's development workflow and disclaimed any
warranty of sandbox branch history.

[1]: http://nvie.com/posts/a-successful-git-branching-model/
[2]: http://git-scm.com/book/en/Git-Branching-Rebasing#The-Perils-of-Rebasing
[3]: http://lwn.net/Articles/328438/