core,tests: change qml register function

In order to address the C++ object directy in qml, a different
registration is needed.

qmlRegisterType, registers the C++ class, allowing qml code to inherit
from it and make qml objects. This is needed for graphical elemnets
like profile and map

setContentProperty, registers the C++ object, thus allowing signals to be
catched.

Signed-off-by: Jan Iversen <jani@apache.org>

tests/testqml.cpp

@@ -37,7 +37,7 @@ int main(int argc, char **argv)
 	argc--;
 
 	// Register types
-	qPref::instance()->registerQML();
+	qPref::instance()->registerQML(NULL);
 
 	// Run all tst_*.qml files
 	return quick_test_main(argc, argv, "TestQML", tst_dir);