match and hyperlinkalize jira tickets in user comment

Change-Id: I32a7b67747a7466bb0985d2c080ab0311fc9313e
Reviewed-on: http://review.couchbase.org/24725
Reviewed-by: Ronnie Sun <ronnie@couchbase.com>
Tested-by: Ronnie Sun <ronnie@couchbase.com>