Updated Kryo to 2.20.
Various fixes to standalone mode and web UI:

- 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 bug in getting slave id out of mesos
Fix for connections not being reused (from Josh Rosen)
Added an option to spread out jobs in the standalone mode.
Fixed deadlock in BlockManager.
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.
Incorporated Matei's suggestions. Tested with 5 producer(consumer) threads each doing 50k puts (gets), took 15 minutes to run, no errors or deadlocks.
Merge pull request #302 from tdas/blockmanager-fix

Blockmanager fix
Fix K-means example a little
Detect correctly when one has disconnected from a standalone cluster.

SPARK-617 #resolve
Fix Java/Scala home having spaces on Windows
Use DNS names instead of IP addresses in standalone mode, to allow
matching with data locality hints from storage systems.
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.
Doc fix
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