mod_pubsub_subscription: support subscribing from a bare JID Allow subscribing from a bare JID on the component instead of only the component host, useful for subscribing to whitelist access model nodes that want to see a particular JID in the from.

This module blocks configured queries that change server state.

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

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