Refactor the code to ES6/ES7

[KleoPetroff]

Refactor all examples to ES6+, including the tests.

Progress

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