mod_http_oauth2: Add support for the "openid" scope This "openid" scope is there to signal access to the userinfo endpoint, which is needed for OIDC support. We don't actually check this later because the userinfo endpoint only returns info embedded in the token itself, but in the future we may want to check this more carefully.

# Introduction

This module sends a [version query][xep0092] to clients when they
connect, and logs the response, allowing statistics of client usage to
be recorded.

Note that since this is per connection, there will be a bias towards
mobile clients on bad connections.

## Example

    info    Running Running Swift version 4.0