Add the "user interface" and a main file

- prototype.rb is the main file, from which we will run the program
- your respective parts entry points are in controllers.rb
- UI class contains useful methods for working with the user, like:
  * choose(message, options): returns the symbol of which option was chosen
  * confirm(message): returns whether the user has confirmed the choice
  * enter(message): returns the user entered string, stripped of whitespace.
  * line(): prints the standard separation line. consistency!
- prototype.json is the database we will use
Merge branch 'master' of https://github.com/nadvamir/GU-PSD3-Team-M