Heroku Buildpack for Rails 3 with assets caching

This is a fork af the official Heroku Buildpack for Ruby apps.

It is modified to cache precompiled assets in Rails 3 apps, and was created to be used in combination with turbo-sprockets-rails3.

Currently based on heroku/ruby (v141)[https://github.com/gregclermont/heroku-buildpack-ruby/releases].