AJAX bindings don't work

[bergmark]

This is because of faylang/fay#251

We should either fix that, or add temporary ajax bindings that actually works.

For now just use flat FFI bindings, like this:

jPost :: String -> Automatic f -> (Automatic g -> Fay ()) -> Fay ()
jPost = ffi "jQuery.ajax(%1, { data: JSON.stringify(%2), type: 'POST', processData: false, contentType: 'text/json', success: %3 })"

[bergmark]

This was fixed in fay-jquery 0.4.0.0.