Integrate Markdown support on site

[zoombear]

Is your feature request related to a problem? Please describe.
Integrate Markdown capability in our CMS backend using this package:
https://github.com/webpro/reveal-md

We must wait until this PR is merged into their package because there is a bug that will not let us install with our version of wagtail:

torchbox/wagtail-markdown#55
torchbox/wagtail-markdown#60

Additional context
The big picture is we'd like to have those creating course materials to be able to just structure their slides out of markdown and upload them onto the backend and have them generate instantly (using our css styleguide) similarly to how RevealJs works:
https://revealjs.com/#/

notes on the MVP
If the reveal md package doesn't look like it's the right solution, you can try an MVP using any other solution! Overall:
In the Admin panel backend, we just want to be able to input markdown for a template and have it generate html on the front end. There are quite a few examples of how to integrate markdown into a wagtail project, example:
https://www.accordbox.com/blog/wagtail-tutorials-8-add-markdown-support/

Feel free to go another route if necessary!