Update 11_2013.tpl.html

Added talk description for Time Series Graphs With Rickshaw
css refactoring

The current css uses lots of tag selectors which
quickly break things when speaker want to use
<ul>'s for their talks description.

Here is an example of a use case that was
previously not supported but now is:

https://github.com/byrichardpowell/hannoverjs.de/commit/2b9f29016404107276d89fe72144ab6ce3cb11bb