Qt Designer: Temporarily disable loading of QDeclarativeView plugin.

Avoid symbol clashes between QtQuick1 and QtQml.

Task-number: QTCREATORBUG-10273
Change-Id: I84d5b378b9e246d67d8114f701ba5d012cbf5cff
Reviewed-by: Eike Ziller <eike.ziller@digia.com>