Use QUrl::fromLocalFile

so that we can open local files on the command line for quick testing.

Change-Id: Ica0fd2242d90e5499c2f1550bc87362f20bf7938
Reviewed-by: Zeno Albisser <zeno.albisser@digia.com>
Reviewed-by: Andras Becsi <andras.becsi@digia.com>