mod_http_oauth2: Keep authorization codes in memory instead of storage Seems excessive to have them in persistent storage for such a short time. Prevents them from leaking in case they never get cashed out.

This module blocks configured queries that change server state.

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

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