* Configure etcd to use a discovery_url to bootstrap the cluster.
* Users can provide discovery_url for individual bay.
* If discovery_url is not provided, it will be generated at runtime
by using a discovery service.
* Admin can set the endpoint of the discovery service in config file.
Default is the public etcd discovery service.
Change-Id: I9dd3a47f6d50ebadf74c4ee65701183f18c9d629
Partially-Implements: blueprint make-master-ha