Use PreferenceFragment for preferences

Much of the functionality of PreferenceActivity has been moved into PreferenceFragment and depricated in PreferenceActivity since API 11 (ICS).
This fixes those deprication warnings.

Patch Set 2: Remove windows line endings

Patch Set 3: Call PrefsActivity to start the Preferences. Let PrefsActivity load the fragment

Change-Id: I26db6ee323acc189306807dcd16a621ea85a33e1