Make the html backend prettier with ipython's css and switch port to 8988

This replaces the matplotlib button images with the ipython images (from jquery ui), screenshot below. Also switched the default port to 8988 so it can be used as a matplotlib backend in an ipython notebook without any issues.

![Screen Shot 2012-12-16 at 9 58 10 PM](https://f.cloud.github.com/assets/1195249/16151/15422a2a-480f-11e2-9e96-98d305403ad8.png)
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