ContentFragment now uses an args Bundle

ContentFragment now uses an args Bundle to receive the layout extra
from the intent used to start ContentActivity, rather than just calling
getActivity().getIntent()….
Also cleaned up the logic, removing the need for the enum flag as this
and the switch statement were redundant.  The OnClick listeners really
took care of the logic so I just needed to use a general string for the
layouts rather than a specific string for each layout, and assign the
extra in the final Fragment