QmlPuppet: Fix build failure for Qt with versions >=5.0 and <=5.2

QQmlType::isComposite and QQmlType::sourceUrl are both unavailable
when used in objectnodeinstance.cpp

Change-Id: I21f66b00348c0535b4779206bd63e363f4b2c225
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>