v3.0.0

v3.0.0

• New feature: support for Rack apps (e.g. Sinatra)
• Removes dependency on Rails
• New feature: deploy strategy class for customizing the :deploy target
• Stage#deploy calls strategy (breaks v2 API)
• Stage#push pushes to Heroku
• If you have a Rails app, you don't have to do anything; the gem will
  automatically configure itself to use the Rails deploy strategy. See
  the README for how to configure you Rack app's Rakefile