Treat qrc protocol the same as file protocol in loading

KUrl's with qrc protocol was not recognized as local files which
triggered mimetype sniffing that doesn't support SVG and break it.

This patch makes qrc urls be treated as local files and modifies the
one place were KURL::isLocalFile depended on the protocol being exactly
"file" and not "qrc".

Task-number: QTBUG-37058
Change-Id: Iad35ebc1fd72049484d2efa1f9caee96060fb236
Reviewed-by: Michael Bruning <michael.bruning@digia.com>