Make couchdb pointer to private branch

Change-Id: If246991ac17e89e653bcf35bf759971bb5ca193e
Reviewed-on: http://review.couchbase.org/26524
Reviewed-by: Junyi Xie <junyi.couchbase@gmail.com>
Tested-by: Junyi Xie <junyi.couchbase@gmail.com>