Detect radios in data usage, control them.

Teach data usage to inspect hardware radios to determine which tabs
and options to display.  Control "Mobile data enabled" state through
ConnectivityManager.  Persist "Show Wi-Fi" state.

Bug: 4599714, 4645276, 4620024, 4599271, 4596812
Change-Id: I4479593d74a8ba744a056767422f1e03182a7a94