Revert "[SPARK-2410][SQL] Merging Hive Thrift/JDBC server"

This reverts commit f6ff2a61d00d12481bfb211ae13d6992daacdcc2.
SPARK-2651: Add maven scalastyle plugin

Can be run as: "mvn scalastyle:check"

Author: Rahul Singhal <rahul.singhal@guavus.com>

Closes #1550 from rahulsinghaliitd/SPARK-2651 and squashes the following commits:

53748dd [Rahul Singhal] SPARK-2651: Add maven scalastyle plugin
Executors of same application in same host should only download files & jars once