mod_register: Don't duplicate welcome subject

Don't include the configured welcome message subject with the body.  If
that's desired, the admin can simply configure it that way.  But if it's
undesired, there would be no way to avoid the subject duplication.

src/mod_register.erl

@@ -420,11 +420,6 @@ send_welcome_message(JID) ->
 		     to = JID,
 		     type = chat,
 		     subject = xmpp:mk_text(Subj),
-		     body = xmpp:mk_text(<<Subj/binary, "\n\n", Body/binary>>)}),
-	  ejabberd_router:route(
-	    #message{from = jid:make(Host),
-		     to = JID,
-		     subject = xmpp:mk_text(Subj),
 		     body = xmpp:mk_text(Body)})
     end.