block sqlalchemy migrate 0.9.2 as it breaks all of nova

Conflicts:
	global-requirements.txt

Closes-Bug: #1368391
Change-Id: Idbe75bc768d91dd1a807d9cf90d82afa0909594e
(cherry picked from commit 70b10edb67ae72bf1f2436ee5abe6ae208ea4d2a)
Merge "block sqlalchemy migrate 0.9.2 as it breaks all of nova" into stable/icehouse