message: prefer xmpp password from settings over login form
  nextcloud/jsxc.nextcloud#6
diff: @@ -531,6 +531,10 @@ jsxc = {
  username = settings.xmpp.username;
  }
  + if (typeof settings.xmpp.password === 'string') {
  + password = settings.xmpp.password;
  + }
  +
  var resource = (settings.xmpp.resource) ? '/' + settings.xmpp.resource : '';
  var domain = settings.xmpp.domain;
  var jid;
  