Replaced StandaloneDeployMode with masterless resource manager using Akka-cluster

Notable changes are:

1) Tests based on LocalSparkCluster needs to be fixed.
2) Master and master ui is removed.
3) A new worker and coarse grained scheduler is added.
4) Akka utils is augmented with akka cluster specific specification.
5) Spark build is updated with akka cluster dependencies.
General refactoring and adding cluster state to worker so that they can be querried via UI.

    1) Removed unused code of related Master.