CDK-515: Added tests for Spark jobs reading from/writing to Datasets.

 * Added spark-core_2.10 under dependency management
 * Implemented tests that use FileSystemDataset and HBaseDataset
I don't think they're needed generally, but I haven't had a chance to test them yet. Also, some of these exclusions were only required by the Hadoop-1 profile. I'll do that testing as part of the next update of the patch.