Cut over to grizzly -> havana

* change BASE_RELEASE and TARGET_RELEASE in grenaderc
* remove work-arounds from devstack.localrc.target
* remove upgrade steps from the upgrade-* scripts
* change references to release names in variables to BASE_ and TARGET_
* remove Javelin check from check-sanity, will return in verify-javelin
  in https://review.openstack.org/#/c/26257/

Fixes bug 1175340

Change-Id: If1523c73ebefeaf3d3e3efdfbc053f47365d123a