Settings: make the launcher preference entry point dynamic

this patch will allow any launcher that has in it's manifest the intent to set the preference catagory to com.cyanogenmod.category.LAUNCHER_PREFERENCES to have it's preferences accessed directly from the settings menu when set as default
this will support most of the major launchers...ie: Apex, Nova, Trebuchet, etc...

Conflicts:
	res/values/strings.xml
	res/xml/settings_headers.xml
	src/com/android/settings/Settings.java