Partial fixes for https://issues.cask.co/browse/CDAP-703 and https://issues.cask.co/browse/CDAP-460. Remainder of work will have to wait until 2.7.0.
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Merge pull request #692 from caskdata/feature/2.6.0_doc_updates

(CDAP-703) Doc Changes due to unification of APIs: MapReduce and Service changes