Better out of the box production support.

@nickjs 

This will ensure that their applications main js file will be precompiled.

It also adds some extra logic to the main Batman controller. Previously it would route all HTML requests to the application's main template. Now if an HTML file is requested as an XHR (i.e. when the HtmlStore requests a partial) it will search the main Asset Pipeline for the file.

I would have preferred to simply fetch the HTML files by name, but when `config.assets.digest` is true (which is the default in production) all the asset file names have an MD5 of their contents appended to them. And this functionality cannot be disabled for specific assets.

Thoughts?