Show error message when the metabox breaks

[hedgefield]

At the request of @atimmer, I've made a mockup for an error message similar to what we now show when MyYoast breaks. It offers a detailed error description and a way to create an issue on our Github repo.

For Premium users, the button should be Contact support and open up a mailto.

[atimmer]

@omarreiss Where should Report bug go? I was thinking GitHub, but this might be too harsh. In Premium is can just go to support like MyYoast.

[omarreiss]

How about we hash the immutable part of the error message (so without browser and datetime) and automatically open a bug in GitHub with that hash in the title? Then we can update the count and have a way to signify users the issue is resolved in an update.

[omarreiss]

And we could refer people to the open issue to follow progress.

[atimmer]

Let's implement this in premium first, with contact support. We'll see what comes from this and we can decide what we want to do here later.