Allow endpoint selection based on meid in message

This change allows the route table to specify message types which
should route based on the MEID (managed equipment ID) in the message
buffer rather than a round-robin list. The special group entry of
%meid in the routing table causes this, and requires the route
generator to suppy RMR with a map of endpoints which currently
manage each ME.

Signed-off-by: E. Scott Daniels <daniels@research.att.com>
Change-Id: I6023cc0363222c85b1b7893c573d6e3f65edd221