Use unicorn for application server
Remove foreman in favor of managing env with capistrano
Remove capistrano in favor of mina for deployments
Update .gitignore and .ruby-version
Update rails and rake

Use spring for loading rails environment
Add settingslogic to manage application settings

  - Remove filters from app/models/settings.rb and add to
    config/initializer/filter_parameter_logging.rb
  - Use settingslogic for secret_token.rb and environment configs
Add notes on contributing
Add example application and database configs
Remove kramdown for now