Provide error message for QUEUE_MEMBER when member is not in queue

When QUEUE_MEMBER is used and the member specified is not in the queue,
Asterisk provides an ERROR message that indicates that the option specified
is not valid. This patch now properly displays an ERROR message that the
member is not in the queue if an interface is specified.

(closes issue ASTERISK-21980)
Reported by: Avraam David


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/11@394345 f38db490-d61c-443f-a65b-d21fe96a405b