Fix ScrollView behavior when used in a Flickable

Setting preventStealing to true for the mouse areas allow
them to be used in a Flickable.

Task-number: QTBUG-37941

Change-Id: I72def1b60e84b4704827b8617095c7cc0370afb4
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@digia.com>
Allow TableView headers to be resized in a Flickable

Setting preventStealing to true will allow headers to be
resized when in a horizontal flickable.

Task-number: QTBUG-37941
Change-Id: I7be45409d96c7940f5f70b311cdedd3a8b7844ed
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@digia.com>