[SPARK-1812] [WIP] Scala 2.11 support

Still work in progress
I think this would then cause the whole thing to be incompatible with Hadoop 1.x. The akka version would have to go with the protobuf version of Hadoop, so the newer version could only work with Hadoop 2.x+. I think this is why akka's protobuf was shaded to begin with? Changing it to 2.5.0 globally would again break Hadoop 1.