[SPARK-1560]: Updated Pyrolite Dependency to be Java 6 compatible

Changed the Pyrolite dependency to a build which targets Java 6.

Author: Ahir Reddy <ahirreddy@gmail.com>

Closes #479 from ahirreddy/java6-pyrolite and squashes the following commits:

8ea25d3 [Ahir Reddy] Updated maven build to use java 6 compatible pyrolite
dabc703 [Ahir Reddy] Updated Pyrolite dependency to be Java 6 compatible
(cherry picked from commit 0f87e6ad4366a8c453a7415bc89399030003c264)

Signed-off-by: Patrick Wendell <pwendell@gmail.com>