Adding Java-accessible methods to Vector.scala

This is needed for the Strata machine learning tutorial (and
also is generally helpful).

Donahue)

Detect when SendingConnections disconnect even if we aren't sending to them

Comment fix

Fixed some of the messages as well as code style.

Also fixed a bug where master was offering executors on dead workers

Conflicts:
	core/src/main/scala/spark/deploy/master/Master.scala

Remove hack workaround for SPARK-668

SPARK-702: Replace Function --> JFunction in JavaAPI Suite.

In a few places the Scala (rather than Java) function class is used.

Don't call System.exit over uncaught exceptions from shutdown hooks

Fixes a broken link in documentation to issue tracker

Added a method to create PartitionPruningRDD.

Ganglia port change

Switch spark_ec2.py to use the new spark-ec2 scripts. 

Move ParallelCollection into spark.rdd package.

Make CoGroupedRDDs explicitly have the same key type.

If combineByKey is using the same partitioner, skip the shuffle.

include jobid in Executor commandline args

STREAMING-50: Support transform workaround in JavaPairDStream

Update issue tracker link in contributing guide