In some part in the code we import objects. In the Openstack style
guidelines they recommend to import only modules.
http://docs.openstack.org/developer/hacking/#imports
Change-Id: I251a19736cf24a7ace40ea10371452f36c0b49b2
currently we can't handle api exceptions, so add mistral api
exception to Recoverable list
Change-Id: I7afeb0b1c900b9fb1854a9eebc768acf0a9c4c89
Closes-Bug: #1483653