fix(docs): updated readme and added instructions for installing global packages

From a support ticket:

> You really need to update the documentation or put the following packages in package.json
> Before being able to run npm run-script build-devgulp-util (successfully, so problem is fixed, yeah), I had to manually install these packages:
 
> through2
> bower
> tildify
> date-time
> stringify-object
> chalk