Added ack call when the cluster state has not changed

The missing call could cause a cluster state update to hang in case there is no change no apply
Made AcknowledgedRequest bw compatible serialization more generic. Enforce same version for readFrom and writeTo
Added support for serialization based on version to AcknowledgedResponse (useful in api that don't support yet the acknowledged flag in the response)
Added support for acknowledgement in update index settings api

Moved also ack warmer tests to more specific AckTests class

Close #3983
Added support for node acknowledgements in delete mapping api

Closes #3984
Added support for acknowledgements to cluster reroute api

Closes #3985