Roaming and background controls under data usage.

Add action items to control mobile data roaming and background data
controls, along with dialogs to confirm.  Still need to fix telephony
to watch for Settings.Secure changes.

Hide "Change cycle" item when viewing app details.  Handle special
case where data usage doesn't want split action bar.

Bug: 4818009, 4979025, 4948767, 5010948
Change-Id: I363ff76a9daf2528d81573cf8d0687719d664bb0