Issued inbox tasks: fixed listing query, to search the complete client.

By default the `CatalogListingView` limits the search to the current context(https://github.com/4teamwork/ftw.tabbedview/blob/master/ftw/tabbedview/browser/listing.py#L543). For the `IssuedInboxTasks` listing is this behavior unwished. Therefore i overwrite the update_config method.

@lukasgraf could you take a look.