Add git-annex & git-annex assistant

I add information on git-annex wich is a more than just a dropbox like. The git-annex assistant creates a synchronised folder on each of your OSX and Linux computers, Android devices, removable drives, and cloud services. The contents of the folder are the same everywhere. It's very easy to use, and has all the power of git and git-annex.
Git-annex logo
Revert "Git-annex logo"

This reverts commit b1c40048686f4b03274b6e222c7f39b1e3890e72.
Add git-annex assistant

Git-annex is a powerfull synchroniser tool, using git and xmpp.
spelling corrections
Merge pull request #27 from Gastlag/master

Add git-annex assistant