Spark 2 support

[harish]

We are in the process of transitioning to Spark 2.0

See the Spark2 branch for the latest state.

Currently all tests are passing, when run in Local TestCuster mode, DruidTest Cluster mode is broken because of dependency incompatibilities between Druid 0.9.x and Spark 2.0. Which means for now you need to separately start a local Druid cluster(just as you had to do prior to v0.4.0)

Will be running more testing and cleanup over the next few days. This branch should be folded into the master branch in around a week's time.

[harish]

The spark2 branch is now folded into master. All tests pass; we have also run a lot of tests on our tpch test cluster.

You can do a build and try the jar on your spark2 cluster. The shell scripts for spark2 are slightly different from spark1.6, please copy the latest version from github onto the sbin folder of your spark2 deployment.