Rewrite SettingsActivity to remove deprecated methods calls

[garysheppardjr]

Class SettingsActivity makes several calls to deprecated methods. In the Android API documentation, it states the following:

"This function is not relevant for a modern fragment-based PreferenceActivity."

Apparently SettingsActivity needs to be rewritten to be more modern. I need to investigate what this means and do the work. This should be doable now that we are on Android 4+ exclusively.