Add support for force and statusCode on redirects

[YoshiWalsh]

According to the documentation for createRedirect, some plugins support the non-standard redirect parameters force and statusCode. It might be nice for us to support these too.

With Redirection Rules, we can support force by adding/removing the HttpErrorCodeReturnedEquals: '404' condition. We can support statusCode by overriding the HttpRedirectCode redirect value.

With redirect objects (#64) we can support force by choosing whether to upload the content object or the redirect object in the event of a conflict. This would require a bit of a change to the upload logic. It's not possible to use redirect objects for anything other than 301, so they would have to still be handled by Redirection Rules.