Blueprint deployments for NameNode Federation Fail

Ambari 2.7.0 will include support for HDFS NameNode Federation deployments, as detailed in:  

AMBARI-22916

Blueprint deployments that attempt to use NameNode Federation currently fail with the following exception: 

{u'status': 400, u'message': u'Topology validation failed: org.apache.ambari.server.topology.InvalidTopologyException: NAMENODE HA requires exactly 2 hosts running NAMENODE but there are: 4 Hosts: [ctr-e138-1518143905142-139109-01-000005.hwx.site, ctr-e138-1518143905142-139109-01-000006.hwx.site, ctr-e138-1518143905142-139109-01-000003.hwx.site, ctr-e138-1518143905142-139109-01-000004.hwx.site]'}

The Blueprint configuration processor needs to be updated in order to properly handle HDFS HA deployments that include Federated nameservices.  This will generally mean that HA deployments can now support more than 2 NameNode instances.