Add deploy:<stage> tasks & Deploy staging by default & Refactoring

* Add `deploy:<stage>` tasks
* Deploy staging with default `deploy` task
* Rename `multistage:create_stagefiles` -> `mutistage:init`
* Remove `config/deploy/development.rb` stage file
I see. On projects that I've worked on, we use continuous integration and deployment. Run all tests, if they pass we merge to master. That then gets deployed to development, then staging if development was successful, then production if staging was successful. This allows us to catch potential deployment issues without impacting a staging server.