When we have finished creating all monitors, if there is only One monitor existing, then disable the ability to toggle the indicator.
When we have finished creating all monitors, if there is only One
monitor existing, then disable the ability to toggle the indicator.

NB: This is for silly people who (for whatever reason) decide that
it's a good idea to try and turn off their Only monitor.

NB: Fixes Phab Ticket T257

Signed-off-by: Chris Michael <177aeddb9e34930a357ecd8dd2d21c80fe280c85@samsung.com>

FlorentRevest/Enlightenment,rvandegrift/e,tizenorg/platform.upstream.enlightenment,tasn/enlightenment,tizenorg/platform.upstream.enlightenment,FlorentRevest/Enlightenment,tizenorg/platform.upstream.enlightenment,rvandegrift/e,tasn/enlightenment,tasn/enlightenment,rvandegrift/e,FlorentRevest/Enlightenment