Core code

-- Add Railtie that configures Rack::Deflate and ServeZippedAssets (custom)
-- ServeZippedAssets is restricted to the public/assets directory, and looks
   to see if the .gz version exists. If so, it asks the Rails Static middleware
   so serve it, then updates PATH_INFO to strip the .gz. It then adds a directive
   to the Cache-Control header to tell Rack::Deflate to leave it alone and not
   recompress it.
-- Rack::Deflate is also enabled for non-asset requests