mod_http_oauth2: Return validation output added in trunk rev 72d7830505f0 It's not fun at all to try to register a client and only get back "failed schema validation", this should help with that.

This module blocks configured queries that change server state.

E.g. to make vCard storage read-only:

``` lua
readonly_stores = {
	vcard = { "vcard-temp", "vCard" };
}
```