Allow branding the 404 not found page for Ideas portal

Sometimes ideas get deleted from the ideas portal. If a customer has an email with a link to the old idea, they get a 404 page. The 404 page is not brandable and contains a message to contact support@aha.io for help instead of an email address at my domain.

Not giving my customer instructions to contact Aha may reduce confusion and increase interaction with my customer so that I can try and explain what happened to their Idea. Aha support staff will not have that contextual information.