[mms] Added Horde_Shutdown - global Horde shutdown function handler.
Revert "[jan] Add a Horde_ShutdownRunner factory on top of Horde_Queue."

This reverts commit 3efc591b42c81bcf3beaaaef76d77fe851707314.

Conflicts:
	framework/Core/package.xml

Per cjh, this is not appropriate use of Horde_Queue.

Replaced w/Horde_Shutdown.
Still think Horde_Queue should be considered a requirement, but at a minimum needs to be listed as optional