Fixes SPARK-723 - Update build to Scala 2.9.3

This builds fine for me.

Though the test suite (i.e., running `sbt/sbt test`) doesn't seem to complete on my Macbook Air, though it doesn't report failed tests (as described in this bug https://spark-project.atlassian.net/browse/SPARK-716)

Fixes https://spark-project.atlassian.net/browse/SPARK-723