docs: installation on Ubuntu

* tested the installation process on Ubuntu Saucy (13.10)

* using 100% more pygments.

Signed-off-by: Yoan Blanc <yoan.blanc@cern.ch>
docs: cleanup of git-workflow

* removing remaining Trac-ish formatting

* removing Trac related features (like closes)i

* added the missing pictures

Signed-off-by: Yoan Blanc <yoan.blanc@cern.ch>