mod_http_oauth2: Record hash of client_id to allow future verification RFC 6819 section 5.2.2.2 states that refresh tokens MUST be bound to the client. In order to do that, we must record something that can definitely tie the client to the grant. Since the full client_id is so large (why we have this client_subset function), a hash is stored instead.

This module produces more detailed HTTP logs for Prosodys built-in HTTP
server. The format is similar to that of Apache and go into Prosodys
normal logs at the `info` level.