im: use full namespace for signal newTextMessage

Qt get confused by namespace if we don't specify it entirely

Change-Id: I20b731b452d5a421eca5d97613de94b97a9f054a
Tuleap: #242

src/media/recordingmodel.h

@@ -86,7 +86,7 @@ public:
    static RecordingModel& instance();
 
 Q_SIGNALS:
-   void newTextMessage(TextRecording* t, ContactMethod* cm);
+   void newTextMessage(::Media::TextRecording* t, ContactMethod* cm);
    void unreadMessagesCountChanged(int unreadCount);
 
 private: