Port autotests from own waitForSignal() to QSignalSpy::wait()

I added QSignalSpy::wait() in Qt 5.0 exactly for this purpose.

Change-Id: I895a92f5f7e4e8554e00f6668e6973cc2c903adf
Reviewed-by: Peter Varga <pvarga@inf.u-szeged.hu>
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>