Fix setting of SPARK_EXAMPLES_JAR

Stage Page updates

Building spark assembly for further consumption of the Spark project with a deployed cluster

Add metrics system for Spark

Conflicts:

	core/src/main/scala/spark/SparkContext.scala
	core/src/main/scala/spark/SparkEnv.scala

Conflicts:

	core/src/main/scala/spark/SparkContext.scala
	core/src/main/scala/spark/SparkEnv.scala

1.change source abstract class to support MetricRegistry
2.change master/work/jvm source class

Scheduler code style cleanup.

SPARK-829: scheduler shouldn't hang if a task contains unserializable objects in its closure

Creates task start events