mod_welcome: Updated to use module:get_option instead of configmanager

plugins/mod_welcome.lua

@@ -6,10 +6,8 @@
 -- COPYING file in the source package for more information.
 --
 
-local config = require "core.configmanager";
-
 local host = module:get_host();
-local welcome_text = config.get("*", "core", "welcome_message") or "Hello $user, welcome to the $host IM server!";
+local welcome_text = module:get_option("welcome_message") or "Hello $user, welcome to the $host IM server!";
 
 local st = require "util.stanza";