daemon: mark some classes and methods 'final'

As suggested by gcc's -Wsuggest-final-types and -Wsuggest-final-methods

Change-Id: I1622857ee53581efd0c6ce3fe93199c72202d817
diff --git a/daemon/face/websocket-channel.hpp b/daemon/face/websocket-channel.hpp
index 1409289..1729841 100644
--- a/daemon/face/websocket-channel.hpp
+++ b/daemon/face/websocket-channel.hpp
@@ -40,7 +40,7 @@
 /**
  * \brief Class implementing WebSocket-based channel to create faces
  */
-class WebSocketChannel : public Channel
+class WebSocketChannel final : public Channel
 {
 public:
   /**
@@ -54,13 +54,13 @@
   WebSocketChannel(const websocket::Endpoint& localEndpoint);
 
   bool
-  isListening() const override
+  isListening() const final
   {
     return m_server.is_listening();
   }
 
   size_t
-  size() const override
+  size() const final
   {
     return m_channelFaces.size();
   }