Merge branch 'scripts-reorg' of github.com:shane-huang/incubator-spark into spark-915-segregate-scripts

Conflicts:
	bin/spark-shell
	core/pom.xml
	core/src/main/scala/org/apache/spark/SparkContext.scala
	core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/CoarseMesosSchedulerBackend.scala
	core/src/main/scala/org/apache/spark/ui/UIWorkloadGenerator.scala
	core/src/test/scala/org/apache/spark/DriverSuite.scala
	python/run-tests
	sbin/compute-classpath.sh
	sbin/spark-class
	sbin/stop-slaves.sh