Simplify error pages styles

Deployed hipache on our network today and was surprised that 
image assets were served directly off dotcloud. Was that intended ?
If so you can close the PR, otherwise i made a few tweaks to pages. 

Now they dont have any image assets at all, just plain page. 
I can add link to dotcloud site if necessary. 

Example:

![Title](http://cl.ly/image/3R2Q2M2T0J3e/Screen%20Shot%202013-10-08%20at%207.48.07%20PM.png)