Added cbsasl_[gs]prop

Change-Id: I1ab2356aa15c628ccd48024e17a0a31624b282eb
Reviewed-on: http://review.couchbase.org/28924
Tested-by: Trond Norbye <trond.norbye@gmail.com>
Reviewed-by: Michael Wiederhold <mike@couchbase.com>