Let "redirect" routes capture subpaths too

[meshy]

If /articles/ moves to /blog/, it would be perfectly reasonable to set up a single URLRedirect to capture and redirect all subpaths rather than having to set up one per URL.

I see two choices:

1. Extend URLRedirect and RouteRedirect to have optional "include subpaths" booleans (I currently favour this approach).
2. Add new redirect models for this use case.