- Each acme account has an index in this table. Before this change, the
index would grow unchecked as orders accumulate. This change removes
orders that have moved out of the 'PENDING' state.
When constructing links we want to read the required host and protocol
information in a dynamic manner from the request for constructing ACME
links such as the directory information. This way, if the server is
running behind a proxy, and we don't know what the exposed URL should
be at runtime, we can construct the required information from the
host, tls and X-Forwarded-Proto fields in the HTTP request.
Inspired by the LetsEncrypt Boulder project (web/relative.go).
