* stable-2.15:
Set version to 2.15.8-SNAPSHOT
ElasticTestUtils: Factor common code out of ElasticReindexIT/ElasticIndexIT
Add support for Elasticsearch 6.5.0
Add Marco Miller as a developer in pom.xml files
Set version to 2.14.17
Change-Id: I0bb655abd6a158f09f670ad65cd37f70479fe483