Docpad Updates

- [x] Update docpad and plugins to latest versions
- [x] Remove external compass watcher and use [docpad-plugin-sass](https://github.com/docpad/docpad-plugin-sass) instead
- [x] Added Bundler Gemfile
- [x] Remove *docpad-plugin-livereload* dependency and use [docpad-plugin-tinylivereload](https://github.com/andruhon/docpad-plugin-tinylivereload) instead
- [x] Update README