Closing the gap on Design Manual and Capital Framework workflows

[jimmynotjim]

Aligned the Design Manual front-end workflow with the Capital Framework front-end workflow

Additions

• Added NPM script to bundle the Jekyll server and Grunt watch as one command

Changes

• Updated the README to better describe our stack
• Updated the README to simplify the front-end instructions
• Updated the README to conform to 80 char line limits (where possible)

Testing

• Pull in this branch and follow the installation instructions
• Run the npm start command
• Open a browser to `http://localhost:4000/

Review

• @Scotchester
• @ascott1

Preview this PR without the whitespace changes

Todos

• We should eventually upgrade this project to use Gulp to keep the front-end workflow more uniform, but this takes care of a lot.

Checklist

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