Refactor the code to ES6/ES7

[KleoPetroff]

Refactor all examples to ES6+, including the tests.

Progress

• [x] Constructor Pattern
• [ ] Module Pattern
• [ ] Revealing Module Pattern
• [ ] Singleton Pattern
• [ ] Observer Pattern
• [ ] Mediator Pattern
• [x] Command Pattern
• [ ] Prototype Pattern
• [x] Facade Pattern
• [ ] Factory Pattern
• [ ] Mixin Pattern
• [x] Decorator Pattern
• [ ] Flyweight Pattern