[selectors] match_kwargs and match_form_params selectors both accept a new `once_is_enough` argument (closes #1990438)
also fix docstring of match_exception and references to selectors in the book.
/*
* 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;
}