Factor out settings

I got carried away a bit last night and changed too many things.
I'm going back and submitting each dividable changes into separate branches.

This branch factors out setTheme to a static method in Utilities, and make all activities set their themes through that method.
Also made activities inflate optionsmenu through xml, which I thought was more clean (I will completely factor this out by making a superclass after I pull request all the changes from last night).
Changed SettingsActivity to handle the theme of Settings and SettingsFragment to handle responding to preference changes.