nitdoc: display redefined methods when mmodule.public_owner is null

Signed-off-by: Alexandre Terrasa <alexandre@moz-code.org>
Merge: nitdoc: display redefined methods when mmodule.public_owner is null

Signed-off-by: Alexandre Terrasa <alexandre@moz-code.org>

Pull-Request: #448
Reviewed-by: Jean Privat <jean@pryen.org>