MB-100 Don't parse fields that we never put to rep document.

Or those that are not actually read.

Change-Id: If18397f786a789eac770437943884c3b29d80f53
Reviewed-on: http://review.couchbase.org/28166
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>