Elasticsearch 6.5.0 - compilation/test failures.

[aasenov]

I was trying to use this driver for ES 6.5.0 as new SQL JDBC driver that is provided from Elasticsearch itself requires Platinium License:
https://www.elastic.co/downloads/jdbc-client
The straight forward compilation doesn't work. I was able to compile without test cases:
mvn package -Dmaven.test.skip=true
after making some changes in the source code. I'm attaching the diff file with my changes (it's generated using diff, not git)
build-ES6.5.0-diff.txt
After that I din't noticed any problems using the driver against my ES cluster, so I didn't make any more changes.

I'll be happy if you apply those changes and we can use master directly and work with latest ES version. Also you can check why tests are failing and what need to be changed there, to ensure that all options are working as expected.