Clarify the installation document.
Clarify the documentation of the Aquilon site
Continue documenting the Aquilon site
Add the release notes for 13.12.
Fix remarks by @ned21.
Mention how to do the upgrades
Merge pull request #55 from piojo/13.12

Release notes for Quattor 13.12
Merge pull request #54 from piojo/aquilon-improve

Clarify the Aquilon documentation.