This is the basic grunt work; code doesn't fully compile yet, since
I'll do some of the more questionable changes in separate commits.

Instead of using "new Configuration()" where a configuration is
needed, let the caller provide a context-appropriate config
object.

This is sort of hackish, since it doesn't account for any customization
someone might make to SparkConf before they actually start executing spark
code. Instead, this will only consider options available in the
system properties when creating the hadoop conf.

Conflicts:
	core/src/main/scala/org/apache/spark/util/FileLogger.scala
	yarn/stable/src/main/scala/org/apache/spark/deploy/yarn/ApplicationMaster.scala

Conflicts:
	core/src/main/scala/org/apache/spark/scheduler/cluster/SimrSchedulerBackend.scala

Conflicts:
	yarn/alpha/src/main/scala/org/apache/spark/deploy/yarn/ApplicationMaster.scala
	yarn/alpha/src/main/scala/org/apache/spark/deploy/yarn/ExecutorLauncher.scala
	yarn/common/src/main/scala/org/apache/spark/scheduler/cluster/YarnClientClusterScheduler.scala
	yarn/common/src/main/scala/org/apache/spark/scheduler/cluster/YarnClusterScheduler.scala
	yarn/stable/src/main/scala/org/apache/spark/deploy/yarn/ApplicationMaster.scala
	yarn/stable/src/main/scala/org/apache/spark/deploy/yarn/ExecutorLauncher.scala

Conflicts:
	core/src/test/scala/org/apache/spark/scheduler/ReplayListenerSuite.scala