gulp-development-task - Adding a dev gulp task
gulp-development-task - Adding a dev gulp task

Summary:- Having a development task for gulp allow us to do TDD a lot quicker and exploratory testing using the html files
Closes https://github.com/facebook/draft-js/pull/242

Differential Revision: D3110358

fb-gh-sync-id: 50f105e0ec9d8e180b057b2f025b33408628ccc7
fbshipit-source-id: 50f105e0ec9d8e180b057b2f025b33408628ccc7

johnmpotter/draft-js,TripleDip/draft-js,tonygentilcore/draft-js,SciMts/draft-js,tonygentilcore/draft-js,facebook/draft-js,davidchang/draft-js,TripleDip/draft-js,brookslyrette/draft-js,johnmpotter/draft-js,davidchang/draft-js,SciMts/draft-js,brookslyrette/draft-js,dirkholsopple/draft-js,dirkholsopple/draft-js