Added option to run http-server

[jimmynotjim]

Added http-server instructions to the readme, a small npm script, and a dependency for that script to make it easier to run a fresh project or test the generator and Capital Framework itself.

Additions

• NPM script to start the server and watch tasks
• Parallelshell package for the NPM script
• Instructions on how to install and run the server.

Testing

• Sym-link the generator by running npm link in the repo root
• In an empty test directory run yo cf, follow the prompts
• In a new terminal window at the test directory root, run npm start
• A server will start using port 7000 with a browsersync session on port 3000

Review

• @contolini
• @anselmbradford
• @Scotchester

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)