SxS back button + No JS

* Carry along the version number via a GET param -- this is needed so we know the version to go "back" to
* Add a template/view class to handle "breakaway" templates for non-JS users
* Use that for the rhs links re: SxS

Known problems:
1. Does not include regulation letter
2. Breakaway content is hidden for non-JS users; pull request is so that @ascott1 can take a look