fix: exclude old org.jboss.netty classes

The akka-remote transitive dependency brings an older io.netty jar into
the assembly causing an occasional "Wrong return type in function"
exception starting SJS:

```
[sparkDriver-akka.actor.default-dispatcher-2] ERROR akka.actor.ActorSystemImpl - Uncaught fatal error from thread [sparkDriver-akka.remote.default-remote-dispatcher-5] shutting down ActorSystem [sparkDriver]
java.lang.VerifyError: (class: org/jboss/netty/channel/socket/nio/NioWorkerPool, method: createWorker signature: (Ljava/util/concurrent/Executor;)Lorg/jboss/netty/channel/socket/nio/AbstractNioWorker;) Wrong return type in function
```

See <sbt/sbt#1518> why the simple exclude of
akka-remote does not work.

project/Dependencies.scala

@@ -13,11 +13,15 @@ object Dependencies {
     "joda-time" % "joda-time" % jodaTime
   )
 
+  // See <https://github.com/sbt/sbt/issues/1518> why the simple exclude for a scala dependency does not work.
+  val excludeAkkaRemotes = Seq("0", "1", "2").map(x => ExclusionRule(organization = "com.typesafe.akka", name = "akka-remote_2.1" + x))
+
   lazy val akkaDeps = Seq(
     // Akka is provided because Spark already includes it, and Spark's version is shaded so it's not safe
     // to use this one
     "com.typesafe.akka" %% "akka-slf4j" % akka % "provided",
-    "com.typesafe.akka" %% "akka-cluster" % akka exclude("com.typesafe.akka", "akka-remote"),
+    // See <https://github.com/sbt/sbt/issues/1518> why the simple exclude for a scala dependency does not work.
+    "com.typesafe.akka" %% "akka-cluster" % akka excludeAll(excludeAkkaRemotes : _*),
     "io.spray" %% "spray-json" % sprayJson,
     "io.spray" %% "spray-can" % spray,
     "io.spray" %% "spray-caching" % spray,