Add gulp option

[jimmynotjim]

This PR adds the option to start a project with Gulp instead of Grunt. It uses pretty much the same exact setup, just with a few tweaks.

Additions

• Add Gulp templates to a /gulp directory
  • Tasks are broken into individual files
  • All tasks use a central config to set up directory structures

    Removals

• None

  Changes

• Adds askForBuildTool option during generation to allow user to choose their build tool
• Moves Grunt template files to a /grunt directory

  Testing

• git checkout gulp option && npm link
• create dummy project, outside this repo, mk test-project && cd_
• run the generator in test-project yo cf making sure to choose Gulp as your build tool
• after NPM & Bower complete, run gulp build
• PROFIT!!!

  Review

• @contolini
• @ascott1
• @KimberlyMunoz
• @sebworks
• Anyone else interested in Gulp???

  Screenshots

Todos

• None

  Checklist

• [ ] Changes are limited to a single goal (no scope creep)
• [ ] Code can be automatically merged (no conflicts)
• [ ] Code follows the standards laid out in the front end playbook
• [ ] Passes all existing automated tests
• [ ] New functions include new tests
• [ ] New functions are documented (with a description, list of inputs, and expected output)
• [ ] Placeholder code is flagged
• [ ] Visually tested in supported browsers and devices
• [ ] Project documentation has been updated (including the "Unreleased" section of the CHANGELOG)

[contolini]

@jimmynotjim This is really exciting! Everything builds fine for me. I filed a PR against your fork with some smoke tests.

[jimmynotjim]

Merged smoke tests and looking good.

[contolini]

:+1: S'all good here.

[jimmynotjim]

Let me test this just once more before we merge it.

[contolini]

Good-to-go?

Let's hope so.

Mergin'.

[ascott1]