Add Constable Badge

[dangoslen]

There are a few ways to do this:

• 1. Would be update the README.md file and updating the badge with a static badge via Shields.io
• 2. Send data to a REST API to generate a dynamic Shields.io
• 3. Send data and create a badge image via a REST API

[dangoslen]

One idea is to use Firebase Realtime Database to store JSON that is publicly available, but only writeable via Constable.

https://firebase.google.com/docs/database/rest/save-data
https://stackoverflow.com/questions/46153828/access-url-without-token-in-firebase-storage

[dangoslen]

Another option is simply writing the badge as an .svg file