- ensure that sqlalchemy.ext is set up for importlater

- ensure that sqlalchemy.ext is set up for importlater

otherwise, it fails if you import from ext before orm:

    from sqlalchemy import *
    from sqlalchemy.ext.declarative import declarative_base
    from sqlalchemy.orm import *

and then do a lazyload, as the ext.baked importlater is not
initialized.

Change-Id: I24dcbfc9ca9022316da28507772562833e45dd95