Settings: Update German translation

Patch Set 1:    * add translations for swap volume keys

Patch Set 2:    * add translations for
                  - Ad-Hoc network
                  - Pie controls

Patch Set 3:    * rename some strings
                * remove unneeded strings
                * fix whitespace error

Patch Set 4:    * rebase

Change-Id: I9816af50b17d728bb5578c98f80465a78ed8e711