Add option for switching between UMS and MTP/PTP mode. (2/2)

Change-Id: I6cf50a41a9a82e40e702f5231ce663636c149613

This adds support for switching between UMS and MTP/PTP.
Settings part (this part) adds option in USB settings (statusbar/notification drawer) for enabling UMS,
and adds setting in Storage menu to enable / disable UMS, this since the USB settings page disappears when enabling UMS.

It's only porting this http://review.cyanogenmod.org/#/c/21115/
Updated simplified Chinese translations

Change-Id: I61ee1b76418b2f1eed4f64eafca28bf4e3ce3f8c
Merge "Add option for switching between UMS and MTP/PTP mode. (2/2)" into jb-mr1
Merge "Updated simplified Chinese translations" into jb-mr1
Fix the message when Bluetooth is turning off while on the tethering menu.

Currently says "Turning Wifi off..."
This change will display "Turning Bluetooth off..." instead.

Change-Id: I398f372bed75f16f0da5b4fa89ce6b67e22012c4
Signed-off-by: Ryan Baxter <rbryanbaxter@gmail.com>
Merge remote-tracking branch 'upstream/jb-mr1' into jb-mr1