Reduce the size of the 404 page

I think we should provide a smaller 404 page as in some cases, the server can generate a lot of 404 pages and users might care a lot about the page size.

People who ever used a mobile data plan know how irritating is to access a large web page, but even more irritating is when the site tries to redirect you the equivalent mobile page and keeps ending up serving you 404 pages that are quite large given the information they offer.

Also, I personally find the search feature in the 404 useless. I tried to use it a couple of times but ended up not finding what I was looking for (Google [seems to be on the same page](http://www.google.com/404) with this). I even asked some of my non-technical friends if they use such a feature. All of them said they don't and they either immediately go back or just close the page and move to the next site.

---

Give the above, I proposed the following <del>[page](http://jsbin.com/IkidERo/1)</del> [page](http://jsbin.com/IkidERo/6).


Some screenshots:

| Browser (OS) | Portrait | Landscape | 
|:---:|:---:|:---:|
|  Chrome (Android 4.1.2) |  <img src="https://f.cloud.github.com/assets/1223565/1290350/5f65d422-302f-11e3-9be6-fafa731ea45a.png" width="100" height="180"> | <img src="https://f.cloud.github.com/assets/1223565/1290351/606fa0d2-302f-11e3-8a40-a8d262da0d09.png" width="180" height="100"> |
|  Safari (iOS 7.0.2) | <img src="https://f.cloud.github.com/assets/1223565/1290340/224cd022-302f-11e3-91c9-344fe0d98ff4.png" width="150" height="200"> | <img src="https://f.cloud.github.com/assets/1223565/1290339/210822fc-302f-11e3-880f-c9ca01eeda93.png" width="200" height="150"> |

Changes:

* simplified the overall design
* remove the Google search functionality as in most cases, it does not provide much value
* <del>minified the code and removed unnecessary tags in order to reduce the file size (the 404 page is intended more as a placeholder and developers should change or customize it according to their needs)</de>
* reduce the overall file size while keeping the gzipped size over 512 bytes to prevent IE from displaying its own custom error page (thanks @mikealmond and @patrickkettner): http://www.404-error-page.com/404-error-page-too-short-problem-microsoft-ie.shtml

Benefits:

* small file size (<del>600</del> 1409 bytes / <del>421</del> 580 bytes gzipped), which is particularly useful when users are on a data plan and / or the server is wrongly configured (e.g.: tries to redirect to a "mobile" version of the web page and ends up serving a 404 page) or developers forget to provide certain files (e.g.: [/favicon.ico](http://zoompf.com/blog/2012/04/instagram-and-optimizing-favicons))
* improved performance (less HTTP requests, less memory consumption, faster rendering, etc.)
* designed to work with all kinds of screen sizes and support IE 6+