This one will validate that the url is under /accounts/, which is
the only part we are going to be excluding from caching once we
move the website to https-only.
This can break things (d'uh).
Do this by introducing a new decorator, @ssl_optional. When this is
present, no SSL redirection will happen, regardless of whether the
access comes in over http or https.
This decorator overrides @ssl_required, but for redability's sake,
never use both at the same time.
