Allow modification of redirect vhosts

hosting_le can't add aliases as SAN's to an LE certificate, because the redirect breaks the lets encrypt validation process.
This issue could be prevented by allowing access to the acme-challenge folder from the redirect vhosts, while still redirecting all other traffic to the target domain.
However, as it stands, there is no hook to allow modification of that part of the config file.

As this prevents the generation of valid certificates for other aliases, this makes server side redirection effectively unusable in combination LE (it will always present certificate warnings when using it with https).