[request] Ensure base_url() always has a trailing '/' (closes #3955093)
Just as an example, cubicweb.ajax.js is clearly written under the
assumption that BASE_URL/baseuri() - which simply contains req.base_url() - has a
trailing /.
[views] Rewrite cw.utils.formContents() with jQuery (closes #3747244)
Use jQuery's serializeArray() method instead. Just keep a bit of
compatibility with FCKEditor...