Add PeerAddressResolver for raft actor

Add PeerAddressResolver for raft actor

For upcoming work to dynamically add peers, the peer address may not be
known and, if the cluster MemberUp has already occurred, no
UpdatePeerAddress message will be sent. We need to be bale to
dynamically resolve peer addresses so I added a new PeerAddressResolver
interface whose instance is obtained from the ConfigParams and used by
the RaftActorContextImpl..

Change-Id: I38807b4b6a59a7cb1359d85a9550cd6e98cb13a4
Signed-off-by: Tom Pantelis <tpanteli@brocade.com>