Redirect user to an error page

The user should be redirected to an error page when the api throws an error
Instead of coding this into every callback we could do something like this in our gh.core.js file when setting up the page:

```javascript
        $.ajaxSetup({
            // Intercept 503 status indicating that the server is down
            'complete': function(xhr, textStatus) {
                if (xhr.status === 503) {
                    // Do some stuff here
                }
            }
        });
````