[Tails-dev] Please review and merge doc/wheezy

This branch adapts our documentation for Tails 1.1, GNOME 3, etc.

branch: doc/wheezy
commits: ee96c15..db03895
ticket: #6980
subtickets:
- #7044: 98dafca
- #7057: 988968f
- #7186: 214d624
- #7187: 33cb018
- #7188: 19a5475
- #7189: 710b95d
- #7190: 78455cf
- #7195: 3811081
- #7196: 94f396a
- #7198: 6070235
- #7200: e9a5af0
- #7201: e9a5af0
- #7203: e9a5af0
- #7205: e9a5af0
- #7207: 76b66bd

Please review and merge into devel.

I'm sorry but I went a bit crazy on the number of tickets but I wanted
to force myself to track all the work on Redmine. In the end I didn't
like it. I should work on finding a better equilibrium :)