Documentation of constent hashing router, see #944

* Document sample to illustrate usage
* Rewrote RouterViaConfig to real DocSpec
* Added configuration snippets for all router types

akka-docs/scala/code/docs/routing/ConsistentHashingRouterDocSpec.scala

@@ -0,0 +1,60 @@
+/**
+ * Copyright (C) 2009-2012 Typesafe Inc. <http://www.typesafe.com>
+ */
+package docs.routing
+
+import akka.testkit.AkkaSpec
+import akka.testkit.ImplicitSender
+
+object ConsistentHashingRouterDocSpec {
+
+  //#cache-actor
+  import akka.actor.Actor
+  import akka.routing.ConsistentHashingRouter.ConsistentHashable
+  import akka.routing.ConsistentHashingRouter.ConsistentHashableEnvelope
+
+  class Cache extends Actor {
+    var cache = Map.empty[String, String]
+
+    def receive = {
+      case Entry(key, value) ⇒ cache += (key -> value)
+      case Get(key)          ⇒ sender ! cache.get(key)
+    }
+  }
+
+  case class Get(key: String) extends ConsistentHashable {
+    override def consistentHashKey: Any = key
+  }
+
+  case class Entry(key: String, value: String)
+  case class EntryEnvelope(entry: Entry) extends ConsistentHashableEnvelope {
+    override def consistentHashKey: Any = entry.key
+    override def message: Any = entry
+  }
+  //#cache-actor
+
+}
+
+class ConsistentHashingRouterDocSpec extends AkkaSpec with ImplicitSender {
+
+  import ConsistentHashingRouterDocSpec._
+
+  "demonstrate usage of ConsistentHashableRouter" in {
+
+    //#consistent-hashing-router
+    import akka.actor.Props
+    import akka.routing.ConsistentHashingRouter
+
+    val cache = system.actorOf(Props[Cache].withRouter(ConsistentHashingRouter(10)), "cache")
+
+    cache ! EntryEnvelope(Entry("hello", "HELLO"))
+    cache ! EntryEnvelope(Entry("hi", "HI"))
+
+    cache ! Get("hello")
+    cache ! Get("hi")
+    expectMsg(Some("HELLO"))
+    expectMsg(Some("HI"))
+    //#consistent-hashing-router
+  }
+
+}