Fix domain swapping

Applies to https://github.com/GigaOM/gigaom/issues/5362

For environments like VIP where the admin ajax url is/can be different from the front end url, we need to do a little dance to make sure it doesn't get changed on the links causing the issue reported.
Arguably you could do the following but it is less obvious what is being done, I think.

```js
new RegExp( '//([^/]+)' );
```