MB-7468 Stats for number of faults experienced by the server.

Change-Id: Iac687659902f95ca6d33152be99104ab321782a2
Reviewed-on: http://review.couchbase.org/23600
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
MB-7468: support both V0 and V1 formats of portsigar replies

So that we're more flexible with advanding manifest of ns_server and
portsigar.

Change-Id: I472b572af7d6bc0cf7ecf4d65d7083dde97709a5
Reviewed-on: http://review.couchbase.org/23729
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>