How can I force Heroku to run assets:precompile if Rails isn't autodetected? <p>I have a Rails 3.1 application with an usual file layout. Heroku detects it as Ruby/Rack rather than Ruby/Rails. <code>assets:precompile</code> isn't run, so pages that require them fail with a javascript error.</p> <p>What do I need in my file structure to trick Heroku into running the precompile task? Or, can I configure a command to run during slug compilation?</p>