Added Maze creation example

I saw that there isn’t anything on disjoint sets or mazes under the
examples so I implemented the process of making a maze.

I have visualized a maze creation before
(https://github.com/nadr0/Maze). I have always been a fan of
visualizing data structures or algorithms and I though this was the
perfect chance!

My code is rather large but it gets the job done.

I

gulpfile.babel.js

 'use strict';
 
+var Promise = require('es6-promise').Promise;
+
 import path from 'path';
 import gulp from 'gulp';
 import uglify from 'gulp-uglify';