mod_http_oauth2: Create proper template for OOB code delivery This also improves security by reusing the security and cache headers, where mod_http_errors/http-message doesn't add such headers. Colors selected by taking rotating the error colors, rrggbb -> ggbbrr

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summary: Store registration events in the audit log
rockspec:
  dependencies:
  - mod_audit
...

This module stores successful user registrations in the audit log provided by
`mod_audit`.