Implement unsupported browser page

We should implement a static page that shows a "Unsupported browser" message when using OAE on IE version 8 or below. Preferably, this would be using an Nginx-based approach to decide when to show that page. Alternatively, an approach similar to what was done for the `noscript` page would be acceptable as well.

The design can be found below:

![error-old-browser-v03a](https://f.cloud.github.com/assets/109850/1614793/cdd5f276-55ef-11e3-983e-6aa6011204e2.png)

Note that the quote should become `If you can't make it good, at least make it look good.`