mod_spam_reporting: Handle unknown or future report types An unrecognised value in the 'reason' attribute would have caused an error. This change makes it mirror the behavior for the previous XEP version.

This module blocks configured queries that change server state.

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

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