title: Asset filtered out and will not be served: add `config.assets.precompile
body: <p>I just migrated my Application to rails <code>4.1.0</code> from <code>4.1.rc2</code>.  Started getting these errors for my JS files</p>
  
  <pre><code>ActionView::Template::Error: Asset filtered out and will not be served: add `config.assets.precompile += %w( my_js )` to `config/application.rb` and restart your server
  </code></pre>