Added router ID. Deregister remote services when router is stopped.

Added ID function to router interface.

Network registry addresses are deregistered when the router is stopped.

Query has been updated to search for particular GW in lookups.

router/router.go

@@ -7,6 +7,8 @@ type Router interface {
 	Init(...Option) error
 	// Options returns the router options
 	Options() Options
+	// ID returns id of the router
+	ID() string
 	// Table returns the router routing table
 	Table() Table
 	// Address returns the router adddress