Move handling of -qmljsdebugger argument to QCoreApplication

Move handling of -qmljsdebugger argument to QCoreApplication

Move handling of -qmljsdebugger= argument from QApplication
to QCoreApplication. It makes sense to allow debugging also
for applications based on QCoreApplication (which we intend
to support in QtDeclarative).

Change-Id: I5a03a4510fc166cea5aad146da673ee0e7cd5d36
Reviewed-on: http://codereview.qt-project.org/5121
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Kent Hansen <kent.hansen@nokia.com>