Upgrade spark to version 1.6.2

[MrAsanjar .]

Hi All,
I have develop a patch https://issues.apache.org/jira/browse/BIGTOP-2565
that would upgrades the current Spark version from 1.5.1 to 1.6.2. I would
greatly appreciate your feedback before I commit the patch. I do realize
both Hive and Phoenix would require changes as well.