function parseQuery(qstr) {
  var query = {};
  var a = qstr.slice(1).split('&');

  for (var i = 0; i < a.length; i++) {
    var b = a[i].split('=');
    query[decodeURIComponent(b[0])] = decodeURIComponent(b[1] || '');
  }
  return query;
}
Take a version from the window query string and load a specific
version of React.

@example
http://localhost:3000?version=15.4.1
(Loads React 15.4.1)