Permanent redirects

Interface to choose pages to setup a 301 redirect for with a minimal integration in the Rails application.

It uses a before filter to check for and perform 301 redirects within the main app, the controller that is utilizing the redirects need to include the concern `Seo::Redirects` to gain this functionality.

Errors raise within the before filter (i.e. `record_not_found`) will be handed to the main Rails Application to handle.

The validations on the redirects prevents:

- specifying multiple redirects using the same origin or destination of another redirect
- using the same origin and destination
- circular redirects (redirects that redirect to a redirect that redirects to the original redirect)