Sprockets Cache Busting

Minor: Silence some harmless Tilt warnings

Automatically expire and recompile all assets when:

* Installing ART
* Updating ART
* Changing ART's Configuration

Ideally, we would only want to expire `.html(.*)` assets, but as far as I can tell, there is no way to get Sprockets to expire *some* assets. 

I believe this is the root cause behind issues: #47 #46 #40 #32

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I'd appreciate it if I could be mentioned as one of the gem authors in the gemspec, because I've done a lot of good work hacking on this gem.