MB-100: logging server name when init_cluster

Change-Id: Icfeeb881f3266f08a525bde6181481f9530e512d
Reviewed-on: http://review.couchbase.org/24786
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>