Initial bot functionality

* The bot now properly joins the management room
* The management room is persisted in the database
* Welcome/help messages are sent in the management room

database/portalkey.go

@@ -0,0 +1,13 @@
+package database
+
+type PortalKey struct {
+	ID       string
+	Receiver string
+}
+
+func (key PortalKey) String() string {
+	if key.Receiver == key.ID {
+		return key.ID
+	}
+	return key.ID + "-" + key.Receiver
+}