Move gulp configuration out of gulpfile.js

Problem/Motivation

Right now everything in the gulpfile is very fragile. Any upstream change in the functionality of the gulpfile will require extensive refactoring if any modifactions have been made. With the current feature-set modifications to the gulpfile are required.

Proposed resolution

Move all configuration out of the gulpfile and allow it to be included either in json or yaml files in the theme.