Delete security groups when deleting the cluster. As many operations
are done on instances in specific security groups, this seems like a
reasonable thing to clean up.
Set default uncaught exception handler to exit.

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.
SPARK-624: make the default local IP customizable
Addressing Matei's comment: SPARK_LOCAL_IP environment variable
Giving the Spark EC2 script the ability to launch instances spread
across multiple availability zones in order to make the cluster more
resilient to failure
Adding comment about additional bandwidth charges
Allow Boto to use the other config options it supports, and gracefully
handling Boto connection exceptions (like AuthFailure)
For size compression, compress non zero values into non zero values.
Tests for MapOutputTracker.
Fix NullPointerException when unregistering a map output twice.
Use hostname instead of IP in deploy scripts to let Akka connect properly
Added a zip() operation for RDDs with the same shape (number of
partitions and number of elements in each partition)
Added zip to Java API
Added a partition preserving flag to MapPartitionsWithSplitRDD.
Adding multi-jar constructor in quickstart
Use external addresses in standalone WebUI on EC2.
Search for a non-loopback address in Utils.getLocalIpAddress
Added maven and debian build files
Include the configuration templates in the debian package
Addressed code review comments