Reload browser if displaying form and $GLOBALS['it_exchange']['product'] is not set.

Another issue that I ran into is a blank super-widget when a form needs to be displayed immediately after a user registers in the ajax super-widget.

**To reproduce:**
1. add product to cart while logged out
2. click checkout and register a new account
3. see a blank super-widget and have to refresh to complete checkout

When inspecting this file I noticed that the `$GLOBALS` variable does not have the `['it_exchange']['product']` data in it unless the user is logged in when the checkout process starts.

I imagine there is likely a better way to get this data within the AJAX request, but for now I used a JS refresh of the page so the user can click "checkout" a second time and see the form (because `$GLOBALS['it_exchange']['product']` is full of info).