Update "Add ES2015 support through Babel" document with last gulpfile.js
Update "Add ES2015 support through Babel" document with last gulpfile.js

anthonybrown/polymer-starter-kit,Ex-ante-Labs/shopper.ninja,StartPolymer/polymer-starter-kit,Ex-ante-Labs/pivot-ahead,lordoftheflies/mlm-portal,abdonrd/polymer-starter-kit,anthonybrown/polymer-starter-kit,lordoftheflies/mlm-portal,abdonrd/polymer-starter-kit,StartPolymer/polymer-starter-kit,markovuksanovic/polymer-starter-kit,StartPolymer/polymer-starter-kit-plus,markovuksanovic/polymer-starter-kit,StartPolymer/polymer-starter-kit-plus,lordoftheflies/mlm-portal,Ex-ante-Labs/shopper.ninja,Serious-Rage/poligomy,Ex-ante-Labs/pivot-ahead,Serious-Rage/poligomy,markovuksanovic/polymer-starter-kit,Serious-Rage/poligomy