Settings: Update German translation

Patch Set 1:    * add QuitHours title
                  http://review.cyanogenmod.org/#/c/31302/
                * add safe headset volume & waiver
                  http://review.cyanogenmod.org/#/c/31368/
                  http://review.cyanogenmod.org/#/c/31576/

Patch Set 2:    * add option to show status bar in expanded desktop
                  http://review.cyanogenmod.org/#/c/31382/
                * rename some strings
                * some layout cleanup

Patch Set 3:    * add backlight curve adjustment
                  http://review.cyanogenmod.org/#/c/30974/

Patch Set 4:    * remove unneeded strings
                * wording changes

Patch Set 5:    * some grammar correction

Patch Set 6:    * remove an changes according to
                  http://review.cyanogenmod.org/#/c/31894/
                  http://review.cyanogenmod.org/#/c/31897/

Patch Set 6:    * final corrections

SCREENSHOT: http://goo.gl/d5P9J

Change-Id: Ia9d416cd8c9612a09d810b9ee95b63c474f985de