mod_http_xep227: Don't require admin privileges to use import/export These APIs always operate on the current user account only. In the future we may want to have a more specific permission check though.

This module blocks configured queries that change server state.

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

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