Output - Webhooks for Report-card

[joenash]

Prefect will provide data for Report Card.

• Webhook to be called when a PR is opened with just a ton of info if possible to the endpoint of POST /queue/exercise. But only post when the "exercise" tag is added so we don't get typo corrections in there.
• To compliment that, one for when a PR is merged or closed. Probably to DELETE /queue/exercise/:id where id is the github repo PR id (https://github.com/campus-experts/open-training/pull/724 this is 724 for example)
• We want a webhook to be called when someone infringes the template and Prefect has to tell them to correct it. So that'll be something like POST /trainee/infringement.