Add addon check

[razzeee]

@pkscout please let me know if this is okay for you.

Then we'll need to add the environment variables

[pkscout]

This looks fine, although someone will have to step me through how to submit updates to the addon repo with this. The md file with the directions only sort of made sense to me.

[razzeee]

That's a problem, can we talk about it and try to sort out, which infos your missing?

[pkscout]

I'm absolutely fine merging this and then figuring it out. This looks like a much easier way to submit updates than what I've been doing. I've just never used tags except on the GitHub site, so I'm not sure what I would have to do with the git pushes to make sure everything is done right. I suspect if someone walked me through it next time there is an update to be done, I'd be fine after that. Shoot, if I can figure this out, I might start using it on some of my own add-ons to make the publishing easier.

[razzeee]

We'll need to sort the variables, I've posted about it in slack