Themes: List ThemeSettings as a valid fragment

This fixes a force close in Settings in tablet mode.

Change-Id: I6542feba0d0fa8491ab9e092a90709d1034ffca8
Settings: preferences use keys, not ids

Change-Id: I23fad40f85235db1fd2c5724ba9d3580828b14d7
Settings: modify AOSP RU translation

Changed "data_usage_menu_metered" and "data_usage_metered_title" to
state it configures Mobile hotspots, not something like APNs.

Change-Id: I40db1da7d6f4a801de5a06c6a5790580da080ebd