Support for "adding hosts" based on blueprint style host_group via Ambari REST API. There are two scenarios to consider for this JIRA:
1) Add hosts based on an existing host in the cluster (and it's blueprint style host_group component layout). This enables the user to add hosts with components similar to existing hosts in the cluster. For example: expand this cluster with these X hosts and make each of these hosts like Y host (components + configs) existing in the cluster.
2) Add hosts based on components + configs. This would be a verbose method that uses blueprint style host_groups and configs to allow you to add hosts to a cluster that do not necessarily have a component layout or config of a similar host existing in the cluster. For example: expand this cluster with these X hosts and make each of these hosts include Y components with Z configs.