Improved use of Boto 

handling Boto connection exceptions (like AuthFailure)

Let EC2 script launch slaves in multiple availability zones

SPARK-624: make the default local IP customizable

Set default uncaught exception handler to exit

Delete security groups when destroying cluster

Among other things, should prevent OutOfMemoryErrors in some daemon threads
(such as the network manager) from causing a spark executor to enter a state
where it cannot make progress but does not report an error.

across multiple availability zones in order to make the cluster more
resilient to failure

are done on instances in specific security groups, this seems like a
reasonable thing to clean up.

matching with data locality hints from storage systems.

SPARK-617 #resolve

Blockmanager fix

Incorporated Matei's suggestions. Tested with 5 producer(consumer) threads each doing 50k puts (gets), took 15 minutes to run, no errors or deadlocks.

1. Changed the lock structure of BlockManager by replacing the 337 coarse-grained locks to use BlockInfo objects as per-block fine-grained locks.
2. Changed the MemoryStore lock structure by making the block putting threads lock on a different object (not the memory store) thus making sure putting threads minimally blocks to the getting treads.
3. Added spark.storage.ThreadingTest to stress test the BlockManager using 5 block producer and 5 block consumer threads.

- Don't report a job as finishing multiple times
- Don't show state of workers as LOADING when they're running
- Show start and finish times in web UI
- Sort web UI tables by ID and time by default

Fix check for existing instances during spark-ec2 launch

Remove unnecessary hash-map put in MemoryStore

Cancel spot instance requests when exiting spark-ec2

Fix minor typos in quickstart and Scala programming guides

a locally computed operation

Conflicts:

	core/src/main/scala/spark/storage/BlockManagerMaster.scala

Added a method to report slave memory status; force serialize accumulator update in local mode.

Conflicts:
	core/src/main/scala/spark/Dependency.scala
	core/src/main/scala/spark/rdd/CoGroupedRDD.scala
	core/src/main/scala/spark/rdd/ShuffledRDD.scala

Allow EC2 script to stop/destroy cluster after master/slave failures