[web form] refactor Form.__init__ so that extra kwargs are set earlier in the process. Closes #2443040
(eg if you want to use them in .session_key)
/*
* cubicweb js mock for unit tests
* This module defines variables and functions used in quite a few places
* in cw js framework that can't be used or guessed without a real CW server
*/
var pageid = 'my-page-id';
function _(message) {
return message;
}