Blacklist: Prevent crash if dialog dismissed with back button

Settings would crash if the dialog was dismissed using the
back button because the view parent was not removed. Add a
listener for the back button event so that the parent is
correctly removed.

Change-Id: Ib379c23051398b95169afe285c11342d7a9836d6
Signed-off-by: Evan Anderson <evan@thelinuxman.us>