Adding Rails app scaffolding
* User model + table
* UserController + new / create / index routes
Email user after they have been added to system
* Use Letter Opener in dev
* Hook after_create in User model, sending through UserMailer
Don't need Letter Opener while under test
Use SQLite in development and test-modes
Updates to UsersController:

* Flash message confirming addition of a user
* Exposed a "reset" action while in development and production
Enabling user-deletion and update

* adding update, edit, and destroy actions to UsersController
* adding delete button to rows in index template
* adding edit template
* updating integration tests
Updating title