Do a standard call on the VLC API.
@param  {options}  options
@param  {string}   call
@param  {array}    args
@param  {Function} cb
function stdCall(options, call, args, cb) {
  var val = '';

  for (var key in args) {
    val += '&' + encodeURIComponent(key) + '=' + encodeURIComponent(args[key]);
  }

  if (call !== undefined) {
    call = '?command=' + call;
  }

  if (call === undefined) {
    call = '';
  }

  if (val === undefined) {
    val = '';
  }

  http.get({
    hostname: 'localhost',
    port: options.httpPort,
    path: '/requests/status.json' + call + val,
    auth: ':' + options.httpPassword,
    agent: false
  }, function(res) {
    if (cb !== undefined) {
      cb(res);
    }
  });
}