mod_pubsub_serverinfo: Fix check for local domain The module was checking whether a host exists, but this may be misleading if our host is loaded before the host that is being checked. This change makes it check the config. This will provide a false positive in the rare case that the host is defined but not activated/enabled. But we don't have an API currently for "is this host configured and enabled?"

Introduction
============

This module turns Prosody hosts into components of other XMPP servers.

Configuration
=============

Example configuration:

``` {.lua}
VirtualHost "component.example.com"
modules_enabled = { "component_client" }
component_client = {
    host = "localhost";
    port = 5347;
    secret = "hunter2";
}
```