cbc: Add config cache option

Change-Id: I60bde01f2056fe634bef87990c8c569949b6fd62
Reviewed-on: http://review.couchbase.org/34994
Reviewed-by: Subhashni Balakrishnan <b.subhashni@gmail.com>
Tested-by: Mark Nunberg <mnunberg@haskalah.org>