Prevent Fonts from Assets from being sorted. Place always at the front

Do this by adding them after sorting the sdcard fonts.
Allow fonts with uppercase ext to be usable
Notify user with a toast when they click a red highlight font
Optimize FontLoader/Adapter for less loading

FontAdapter:
-- Place Font Loader initialize in the constructor.

SettingsActivity
-- Make FontLoader and Adapter static and only init them if they are
null when initializing. Allows reusing variables until the app is
closed and speeds up settings loading time.
Reuse FontLoader by passing as an argument to FontAdapter