Spark-2447 : Spark on HBase

Add common solution for sending upsert actions to HBase (put, deletes,
and increment)

This is the first pull request: mainly to test the review process, but there are still a number of things that I plan to add this week.

1. Clean up the pom file
2. Add unit tests for the HConnectionStaticCache

If I have time I will also add the following:
1. Support for Java
2. Additional unit tests for Java
3. Additional unit tests for Spark Streaming
The param name is `rdd` rather than `RDD[t]`. I don't think scaladoc / javadoc will parse that.