refactor some config based on updated thoughtbot conventions

* add i18n.rb to test support
* re-add profile worker for delayed_jobs
* make load_tasks more generic using Rails.application
* clean up application.rb
* include more framworks (active_model & action_view)
* use i18n available locales
* use exist? instead of exists? in boot.rb
* use more generic Rails.application for initiliazation in boot.rb
* use ActiveRecord::Base default configuration for db if none defined
don't define params, use convention of adding listing them in options