Add plugin scaffolding care of WP-CLI

`.travis-ci.yml` from https://github.com/Automattic/wp-cli-cron-control-offload/blob/a5ad98706a1d744791843b910f6fdee083c2e600/.travis.yml

It's more lines of code and harder to decifer. But that was a fun exercise.

Something is really wrong if this happens. Means the `intercept()` method is loaded on the wrong screen.