Approve room invitations

We use to rely on Empathy for this but as we plan to allow users to be
connected on IM without having Empathy running the Shell should do it now.

https://bugzilla.gnome.org/show_bug.cgi?id=653740

src/shell-tp-client.h

@@ -111,5 +111,8 @@ void shell_get_contact_events (TplLogManager *log_manager,
                                guint num_events,
                                GAsyncReadyCallback callback);
 
+void shell_decline_dispatch_op (TpAddDispatchOperationContext *context,
+                                const gchar *message);
+
 G_END_DECLS
 #endif /* __SHELL_TP_CLIENT_H__ */