introduce base64 random names

- remove Props.randomName and associated logic
- ActorRefFactory contains AtomicLong which is used to generate unique
  children names
- base64-like encoding is used with reverse “digit” order
- disallow given names which are null, empty or start with ‘$’
- random names start have ‘$’ prepended (‘$’ not being one of the 64
  characters)
- special marker “$_” for tempPath until “/tmp” supervisor is introduced
- TestActorRef uses globally unique “$$” prefix, as it creates actors
  beneath any supervisor as instructed by the user

akka-remote/src/main/scala/akka/remote/Remote.scala

@@ -188,7 +188,7 @@ class RemoteSystemDaemon(remote: Remote) extends Actor {
       Props(
         context ⇒ {
           case f: Function0[_] ⇒ try { f() } finally { context.self.stop() }
-        }).copy(dispatcher = computeGridDispatcher), app.guardian, app.guardian.path / Props.randomName, systemService = true) ! payloadFor(message, classOf[Function0[Unit]])
+        }).copy(dispatcher = computeGridDispatcher), app.guardian, app.guardian.path / app.provider.tempPath, systemService = true) ! payloadFor(message, classOf[Function0[Unit]])
   }
 
   // FIXME: handle real remote supervision
@@ -197,7 +197,7 @@ class RemoteSystemDaemon(remote: Remote) extends Actor {
       Props(
         context ⇒ {
           case f: Function0[_] ⇒ try { sender ! f() } finally { context.self.stop() }
-        }).copy(dispatcher = computeGridDispatcher), app.guardian, app.guardian.path / Props.randomName, systemService = true) forward payloadFor(message, classOf[Function0[Any]])
+        }).copy(dispatcher = computeGridDispatcher), app.guardian, app.guardian.path / app.provider.tempPath, systemService = true) forward payloadFor(message, classOf[Function0[Any]])
   }
 
   // FIXME: handle real remote supervision
@@ -206,7 +206,7 @@ class RemoteSystemDaemon(remote: Remote) extends Actor {
       Props(
         context ⇒ {
           case (fun: Function[_, _], param: Any) ⇒ try { fun.asInstanceOf[Any ⇒ Unit].apply(param) } finally { context.self.stop() }
-        }).copy(dispatcher = computeGridDispatcher), app.guardian, app.guardian.path / Props.randomName, systemService = true) ! payloadFor(message, classOf[Tuple2[Function1[Any, Unit], Any]])
+        }).copy(dispatcher = computeGridDispatcher), app.guardian, app.guardian.path / app.provider.tempPath, systemService = true) ! payloadFor(message, classOf[Tuple2[Function1[Any, Unit], Any]])
   }
 
   // FIXME: handle real remote supervision
@@ -215,7 +215,7 @@ class RemoteSystemDaemon(remote: Remote) extends Actor {
       Props(
         context ⇒ {
           case (fun: Function[_, _], param: Any) ⇒ try { sender ! fun.asInstanceOf[Any ⇒ Any](param) } finally { context.self.stop() }
-        }).copy(dispatcher = computeGridDispatcher), app.guardian, app.guardian.path / Props.randomName, systemService = true) forward payloadFor(message, classOf[Tuple2[Function1[Any, Any], Any]])
+        }).copy(dispatcher = computeGridDispatcher), app.guardian, app.guardian.path / app.provider.tempPath, systemService = true) forward payloadFor(message, classOf[Tuple2[Function1[Any, Any], Any]])
   }
 
   def handleFailover(message: RemoteSystemDaemonMessageProtocol) {