Add the Q_OBJECT macro to the notifiers

The notifiers are derived from QObject and shall have the Q_OBJECT
macro.

Tested the build on Windows, Windows CE, Android with Qt4 and then Qt5.

Change-Id: Ie860a02cb5e73b9af62e0f0b5de379e34c077c0e
Reviewed-by: Laszlo Papp <lpapp@kde.org>
Reviewed-by: Sergey Belyashov <Sergey.Belyashov@gmail.com>
Replace the reinterpret_cast to qobject_cast for the QObject's

Change-Id: I883838a264345a6b3a1d73725f1385981513870b
Reviewed-by: Sergey Belyashov <Sergey.Belyashov@gmail.com>
Reviewed-by: Laszlo Papp <lpapp@kde.org>