MB-8217: Add addrm, setrm, and delrm commands

Change-Id: Iebcc47328ba7cc5d84fe95bec0e379fef1b5b560
Reviewed-on: http://review.couchbase.org/26286
Reviewed-by: Chiyoung Seo <chiyoung.seo@gmail.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>