Allow custom submit handler to be used after validation is done

I'm not sure we need this functionality?

Developers can add their own submit handler to their forms in their js files like this:

(function ($, Drupal) {
  'use strict';

  Drupal.behaviors.cvCustom = {
    attach: function (context) {
      $(context).find('form').each(function() {
        var validator = $(this).validate();
        validator.settings.submitHandler = function(validator, form, event) {
          alert('custom submit handler');
        };
      });
    }
  };
})(jQuery, Drupal);

Ah, strange. I'll try to create a proof of concept later on. If I can get it to work fairly simple, I'll add the method to the readme. If not, I'll have another look at the patch.

Attached is a proof of concept that works for me (latest dev version of clientside validation 8.x-1.x. Can you confirm it works for you too?

If it does we might want to document this.