MB-9198: implemented new-style terse bucket info

With nodesExt as specified at:
https://docs.google.com/document/d/1FhGusVWYCAL3Esey4vYCnaV8rAaZhw4XAtJ0w4hftyE/edit

Change-Id: Ifb280f3881d81f77c8d92a90b12d0c54c26c2590
Reviewed-on: http://review.couchbase.org/37363
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>