remove references to Remote* from akka-actor

- moved RemoteInterface.scala into akka-remote, not needed anymore since
  the plugin is loaded as ActorRefProvider now
- removed some old unused imports
- split out remote aspects from Deployer & DeployerSpec into
  RemoteDeployer & RemoteDeployerSpec (the latter in akka-remote)
- created a ticket for cleaning up the rest, mostly remove all
  occurrences of “remote” and “cluster” from akka-actor in this way

All of this was triggered by wanting to:
- change the signature of RemoteSupport.send to require a RemoteActorRef
  recipient

akka-remote/src/main/scala/akka/remote/netty/NettyRemoteSupport.scala

@@ -367,10 +367,11 @@ class NettyRemoteSupport(_system: ActorSystem, val remote: Remote) extends Remot
   protected[akka] def send(
     message: Any,
     senderOption: Option[ActorRef],
-    recipientAddress: RemoteAddress,
-    recipient: ActorRef,
+    recipient: RemoteActorRef,
     loader: Option[ClassLoader]): Unit = {
 
+    val recipientAddress = recipient.path.address.asInstanceOf[RemoteAddress]
+
     clientsLock.readLock.lock
     try {
       val client = remoteClients.get(recipientAddress) match {