Speed up ClusterChangesHandler

* added performance test
* improved assign_vip
* improved geting controllers in CheckBeforeDeployment
* improved checking untagged networks
* changed name of property default_group on to default_group_id
* correct tests and add new

Change-Id: Iba10fdae455c3f19a71cbcdc88f8cd370ffd1993
Closes-Bug: #1384623
Merge "Speed up ClusterChangesHandler"