Add router to make it easier to set up routing info

- Using the router, the dispatch is not done anymore by receiving from
  receive channel, but by registering callback functions in routers,
  with matchers.
- Make IQPayload a real interface to make it easier to match namespaces.
- The StreamManager Run command is now blocking, waiting for StreamManager
  to terminate.

auth.go

@@ -102,12 +102,15 @@ type auth struct {
 }
 
 type BindBind struct {
-	IQPayload
 	XMLName  xml.Name `xml:"urn:ietf:params:xml:ns:xmpp-bind bind"`
 	Resource string   `xml:"resource,omitempty"`
 	Jid      string   `xml:"jid,omitempty"`
 }
 
+func (b *BindBind) Namespace() string {
+	return b.XMLName.Space
+}
+
 // Session is obsolete in RFC 6121.
 // Added for compliance with RFC 3121.
 // Remove when ejabberd purely conforms to RFC 6121.