mod_firewall: spam-blocking.pfw: Remove requirement for invites to have no body Some clients (e.g. Gajim) send a body, which I guess makes sense. The bare JID sender check should already make it hard to bypass this (i.e. a normal client putting muc#user into a normal chat message shouldn't bypass the usual message filters).

This module lets you block connections to any remote servers not on a
whitelist.

``` {.lua}
modules_enabled = {
    -- other modules --
    "s2s_whitelist",

}
s2s_whitelist = {
    "example.org",
}
```