Cluster scaling implementation

The following is supported:

* Scaling node groups if they contain tasktracker or datanode only
* Add new node group to cluster
* Validation
* Rollback

Implements blueprint manual-cluster-scaling

Change-Id: I3838db4b05afa3583db0d059541c00e75cc6cfe2
Anti affinitity group field name fixed in validation schema

Change-Id: I1823a3755e98953bb8acf193b2727bc5baf23ec6
Merge "Cluster scaling implementation"
Merge "Anti affinitity group field name fixed in validation schema"