added ajax-events and permissions for these events

Part 1

• in IDE:
  1. open /themes/advanced/in-commerce/elements/content_boxes/checkout/shipping_address.elm.tpl template for editing
  2. change OnUpdate to OnUpdateAjax in it and save changes
• on Front-End:
  1. add a tangible product to the Shopping Cart
  2. press Proceed to Checkout button to go to the Shipping Information step
  3. fill all fields, except Zip Code
  4. press "Update Address" button
  5. confirm, that page after reload displays correct JSON data - {"status": "FAILED","uploader_info": [],"field_errors": {"ShippingZip": "Field is required"}}

Part 2

• in IDE:
  1. revert changes made to /themes/advanced/in-commerce/elements/content_boxes/checkout/shipping_address.elm.tpl template
  2. open /themes/advanced/in-commerce/elements/content_boxes/checkout/billing_options.elm.tpl template for editing
  3. change OnProceedToPreview to OnProceedToPreviewAjax in it and save changes
• on Front-End:
  1. fill the missing Zip Code Field
  2. select shipping type
  3. proceed to Billing Information step
  4. fill all fields, except Zip Code
  5. press "Proceed to preview" button
  6. confirm, that page after reload displays correct JSON data - {"status": "FAILED","uploader_info": [],"field_errors": {"BillingZip": "Field is required"}}