tf300t: Add multi-user interface and more power menu options

 PS:2 Remove whitespaces

Change-Id: I0b5a29516b7c325668fffa42b40ca105ddbf681b
tf300t: re-enable DeviceKeyhandler so we have dock keyboard suppprt

Since https://gerrit.omnirom.org/#/c/10823/ is committed we can use the devicekeyhandler class for the special dock keys.

Change-Id: Ie1fa9d1db03ca4a857a1d678c5b8197894cd4b41
Merge pull request #2 from omnirom/android-5.0

merge into lp5.0