Force earlier version of sqlalchemy
Force earlier version of sqlalchemy

Set the version of sqlalchemy to be earlier than the 0.8 beta as it
is incompatible with the latest available sqlalchemy-migrate and as
a result run_tests.sh does not run any tests.

Change-Id: I9c5515b76d35e4999f81d71e82f818685efe54ea

hyakuhei/cleantox,hyakuhei/cleantox,zancas/hacking,zancas/hacking,openstack-dev/hacking,emonty/oslo-hacking,emonty/oslo-hacking,openstack-dev/hacking