Support HTML5 `formaction` attribute

[alpha1]

Pjax does not use formation on a input type="submit".

Steps to duplicate:

1. Create Form with pjax submission with action being a different page or query.
2. Test Form. It will work and use the form's action attribute to change the url.
3. Now add a submit button with a formaction different than that of the form itself.
4. Submit via Pjax. The URL from the form's action's attribute will be used rather than the formaction on the submit.

[mislav]

This library doesn't yet support emerging HTML5 standards like formaction. It might in the future.

[raphaelm22]

I solved the problem like this:

$(document).on("submit", "form[data-pjax]", function (event) {
var config = {};
var url = $(":input[type=submit][formaction]:focus", $(this)).attr("formaction");
if (url) {
config.url = url;
}
$.pjax.submit(event, "#Container", config);
});