[TEST] Verify the flush reponse
[TEST] Add FailureMarker to test listeners so -Dtests.failfast works
[TEST] Removed incorrect assertion (it is expected that the flush doesn't execute on all shard copies, because we don't wait for green status)
Added link to "native" ES client
Docs: Linked to fielddata formats from core types

Closes #6489
Facets: deprecation.

Users are encouraged to move to the new aggregation framework that was
introduced in Elasticsearch 1.0.

Close #6485
[DOCS] Clarify the trade-off of the `disk` doc values format.