new jscs rule
New style for history tab.

- Now everything it's in a single place (the tab), no popups anymore.
- On the left you can see the history of commits with users avatars took from Gravatar or generated by CSS (user choice).
- Clicking on a commit, the choosen one is loaded on the right side of the history tab.
- Comments are now formatted using markdown.
some fixes to rebase
rebase implementation