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
The previous version of the patch used that method, but that method doesn't set the output format class as that's only a method on `Job`. Here's the relevant section of code on the `DatasetKeyOutputFormat` side:

https://github.com/kite-sdk/kite/blob/master/kite-data/kite-data-mapreduce/src/main/java/org/kitesdk/data/mapreduce/DatasetKeyOutputFormat.java#L155-L169

Note the `job.setOuputFormatClass()` in `DatasetKeyOutputFormat.configure(Job)` which doesn't exist in `DatasetKeyOutputFormat.configure(Configuration)`.