I'm having 2nd thoughts about this approach. This will cause all of tabzilla to be cached separately for the `transbar` on and off cases. What if instead of a query param we used a data attribute on the script tag? I believe it's quite easy to get a reference to the script tag that includes the code. This would allow us to always send the same JS,and toggle the feature easily as well. For example:

```jinja
<script src="{{ settings.CDN_BASE_URL }}{{ url('tabzilla') }}?build={{ BUILD_ID_JS }}" data-transbar="on"></script>
```

Alternately we could add such a data attribute to the `#tabzilla` element on the page, or even just a class. 

@kyoshino thoughts?