Launch theme chooser that supports cyngn.intent.category.APP_THEMES

If we receive an ActivityNotFound exception we will simply show
the theme settings fragment.

Change-Id: I38bf6857125cdeda310e3bb5614fd6adaba8265f

Conflicts:
	src/com/android/settings/Settings.java
Merge remote-tracking branch 'upstream/kk4.4' into kk4.4