Add Gitpod to simplify contributor onloading

[JesterOrNot]

This PR adds a Gitpod setup to the repository this will allow contributors to contribute with the push of a button with the project already build, all from within a browser

Try It Out
https://gitpod.io/#https://github.com/JesterOrNot/dockerfilelint

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.

---

Sean Hellum seems not to be a GitHub user. You need a GitHub account to be able to sign the CLA. If you have already a GitHub account, please add the email address used for this commit to your account.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}