Delay setting the DBusConnection for a DBusObject

Previously, the DBusconnection had to be set at construction time and could
not be changed over the DBusObject life time. Now a new connection can be
set anytime and as often as required.
The shared ownership is now also properly implemented by shared pointers.

ref T291

src/xswiftbus/weather.cpp

@@ -14,10 +14,8 @@
 
 namespace XSwiftBus
 {
-    CWeather::CWeather(CDBusConnection *dbusConnection)
-        : CDBusObject(dbusConnection)
+    CWeather::CWeather()
     {
-        registerDBusObjectPath(InterfaceName(), ObjectPath());
     }
 
     //! Set cloud layer