mod_admin_blocklist: Add config option for which role(s) to consider (0.12+) Fixes that in trunk, a "prosody:operator" (formerly a global admin) is not considered a "prosody:admin", so those were not included in the set.

This module blocks configured queries that change server state.

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

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