test-report target for XML test reports

on JRuby. This is quite ugly: JRuby has its own version of JLine which
is older than Scala's, and JLine changed API in such a way that code
written for the new version won't compile with the old one and vice
versa. Sadly, this might be a reason to drop buildr, unless we can
package a JRuby with it that uses the right version, or we ask people to
only use the C Ruby version of buildr (which doesn't work on OS X right
now!)

phase of DfsShuffle.

Fixed a small bug in DFS shuffle -- the number of reduce tasks was not being set based on numOutputSplits

well as versions of the shuffle operations that set the number of splits
automatically.

don't all hit the same nodes at the same time.

These tasks were being subjected to delay scheduling but then counted as
having been launched on a preferred node. The solution is to have a
separate queue for them and treat them as preferred during scheduling.

Conflicts:
	src/scala/spark/SparkContext.scala

Using the latest one from Matei.

are used to create an initial copy of each config file if the user does
not have one. This way, users won't accidentally commit their changes to
config files to git.

use this. Closes #12.

Simplified UnionRDD slightly and added a SparkContext.union method for efficiently union-ing a large number of RDDs

optional constructor parameter, so that the scheduler is guaranteed that
a Spark home has been set when it first builds its executor arg.

SparkContext and have the master node serve those to workers.