Introduce gulp as BWC's task runner for builds. Old grunt tasks are stubbed out, but stay in the repository for review purposes.

• Added simple minification to browserify build step.
• Updated package.json -- Best to remove your current node_modules and run 'yarn install'
• Break out source maps from built dist files for debugging purposes

If gulp fails to run in your environment, install gulp globally: 'npm install -g gulp-cli'