Visual showcases of the components

Very experimental test page of the major components of the app. We are using something very similar at work where we have bunch of themes, different typefaces and it makes so much sense to have it all in one page for quick visual test.

I'm still not sure how big will be that page or how many different things will be added so lets see as we go..

Missing important things:
- [ ] Forms
- [ ] Filter links (like in [User List](https://gae-init.appspot.com/user/?active=True&order=-modified))
- [ ] Pagination

### [test.gae-init.appspot.com/admin/test](http://test.gae-init.appspot.com/admin/test/)

P.S. Obviously this has nothing to do with unit testing, but because it has something to do with visual testing that's why it's called test and not showcase.. :)