[SPARK-1812] [WIP] Scala 2.11 support

Still work in progress
I was not aware of Hadoop-1 specific dependency on 2.4.1. Going by what you are saying, my guess is this change will not work with Hadoop 1. I am only testing with "mvn test" within Spark as of now.

So someone has to release a shaded protobuf version of either Hadoop1 or akka to reconcile this problem. That would be necessary before final merge. In the mean time I shall continue to make progress ignoring the Hadoop-1 compatibility problem (after all bulk of the work is yet to be started, in repl). Once a shaded-protobuf is released (akka or hadoop1, whichever) it is just a trivial change in pom.xml then.