mod_muc_badge: If room has no title use localpart of room's jid (fixes #1767) Without this patch Prosody shows an HTTP 500 error (Lua 5.1) or a "nil" label in the SVG badge (Lua 5.2) if room has no title set.

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

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