Make Cloud Loadbalancer properties updatable

Several Cloud Loadbalancer properties that are updatable in the Cloud
Loadbalancers API were not updatable in the Heat resource.  Add
handle_update for each of these properties.

Change-Id: Ie1de3461ef2114b64195f9cb906caebd853be381
Closes-Bug: #1382665
Merge "Make Cloud Loadbalancer properties updatable"