[WIP] Add special HTML pages for when a model result is not found or is incompatible

[GoFroggyRun]

This PR tries to close #869. Two HTML pages are added to TB and CCC respectively, where the content of the page suggest an option to re-create outdated results.

[GoFroggyRun]

Here's a preview for TB version:

@hdoupe could you take a look at these pages? Feel free to modify the content if you'd like.

Do you find these pages sufficient for you to render in view.py?

[GoFroggyRun]

I also noted that CCC and TB are sharing the same header: see here. Does it make sense to break TB's header into two pieces, one for TB and the other for CCC, and place them in their respective directories?

[hdoupe]

@GoFroggyRun these look good. I think we can go ahead and merge this. I'll update the back-end so that these pages are rendered on exceptions. I'll also tweak the language some. Thanks for the quick response on this PR.

I think it does make sense to break up the headers. Would you mind opening a separate PR to do this? There's a lot of apps referencing code in other apps in both in the front-end and in the back-end. I think it's a good idea to draw a clear line between the different apps and pull the shared code into a central place.