Refactoring

Put a bunch of files under folders `admin`, `scheduling`, `maintenance`, and `private_lessons`.  Feel free to organize them into other folders if these don't make sense but try to keep it consistent
It loads the files directly from the sub directories I put them in that way it can use them like `User` instead of a namespaces `Admin::User`

source: http://stackoverflow.com/questions/18934115/rails-4-organize-rails-models-in-sub-path-without-namespacing-models