Updated Kryo to 2.20.
SPARK-624: make the default local IP customizable
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.
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
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.
Merge pull request #306 from admobius/master

Delete security groups when destroying cluster
Merge pull request #305 from woggling/exit-on-uncaught

Set default uncaught exception handler to exit
Adding comment about additional bandwidth charges
Addressing Matei's comment: SPARK_LOCAL_IP environment variable
Merge pull request #304 from mbautin/configurable_local_ip

SPARK-624: make the default local IP customizable
Merge pull request #308 from admobius/multi-zone

Let EC2 script launch slaves in multiple availability zones
Allow Boto to use the other config options it supports, and gracefully
handling Boto connection exceptions (like AuthFailure)
Merge pull request #309 from admobius/use-boto-config-file

Improved use of Boto 
Added maven and debian build files
Include the configuration templates in the debian package
Addressed code review comments
Tests for MapOutputTracker.
Fix NullPointerException when unregistering a map output twice.
Updated versions in the pom.xml files to match current master
For size compression, compress non zero values into non zero values.