Revert "[mms] Added session_version hook."

This reverts commit d4e52cb9e88f2b942e64537ab02c8b71f10f7a9d.

Conflicts:
	framework/Core/package.xml

Nevermind.  As was correctly pointed out to me, this can be handled via
the existing $conf['session']['name'] parameter.
fix reST
Add blurb about expiring pre-existing sessions