Heavily inspired by Hadoop cluster scripts ;-)

Merge Akka reference.conf files in sbt assembly task

This resolves an issue where running Spark from
the assembly jar would cause a "No configuration
setting found for key 'akka.version'" exception.

This solution is from the Akka Team Blog:

http://letitcrash.com/post/21025950392/

Also cleaned up a few formatting things throughout block manager code.

Conflicts:

	core/src/main/scala/spark/Accumulators.scala

The BlockManager's put seems to be slightly asynchronous, which can
cause it to fail this test by not removing stuff from the cache before
we put the next value. We should probably change the semantics of put()
in this case but it's hard right now. It will also be hard for
asynchronously replicated puts.

Changed union() methods on lists to take a separate "first element"
argument in order to differentiate them to the compiler, because Java 7
considered it an error to have them all take Lists parameterized with
different types.

Fixed bugs in block dropping code of MemoryStore and changed synchronized HashMap to ConcurrentHashMap in BlockManager.

Java API

- Add override keywords.
- Cache RDDs and counts in TC example.
- Clean up JavaRDDLike's abstract methods.

Conflicts:

	core/src/test/scala/spark/MesosSchedulerSuite.scala

Conflicts:

	core/src/test/scala/spark/ShuffleSuite.scala

Add missing Scala Map to java.util.Map conversions.

- Replace JavaLR example with JavaHdfsLR example.
- Use anonymous classes in JavaWordCount; add options.
- Remove @Override annotations.

Add distinct() method to RDD.

Fix bug in DoubleRDDFunctions.