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/RemoteConnectionManager.scala

@@ -149,5 +149,5 @@ class RemoteConnectionManager(
   }
 
   private[remote] def newConnection(remoteAddress: RemoteAddress, actorPath: ActorPath) =
-    RemoteActorRef(remote.system.provider, remote.server, remoteAddress, actorPath, None)
+    new RemoteActorRef(remote.system.provider, remote.server, actorPath, None)
 }