mod_http_oauth2: Support HTTP Basic auth on token endpoint This is described in RFC 6749 section 2.3.1 and draft-ietf-oauth-v2-1-07 2.3.1 as the recommended way to transmit the client's credentials. The older spec even calls it the "client password", but the new spec clarifies that this is just another term for the client secret.

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.