Update German translation.

Wording taken from phone app and adapted for messages.

Change-Id: Ib8b9826a36ba45feaa6d3698ee0e5210044367ea
Merge "Update German translation." into cm-10.2
Merge branch 'cm-10.2' of https://github.com/CyanogenMod/android_packages_apps_Mms into cm-10.2