Use @fastly/cli in the starter kit

[harmony7]

This PR makes changes:

• Changes to package.json to enable usage without a global installation of the Fastly CLI:

  • Adds @fastly/cli to devDependencies so that it's available when using the starter kit, as a tool used to build and run or publish the application.
  • Makes sure that scripts contains start and deploy scripts as applicable.

• Adds instructions to the README describing how to initialize an application using the starter kit, as well as how to run it locally or publish it to a Fastly service, as applicable.

• Adds post_init script to run npm install if it was not present.