Bootstrap

How are folks feeling about this?  Should we merge it so the new website design can be part of the 1.1 release?

There's a preview at http://www.teallabs.org/diagrams/

The issues I know of are with the tutorial titles (header tags) and the footer crediting tools we use to make the website.  I've removed both.  The problem in both cases is that we were using the templating feature of hakyll / pandoc to insert them.  To render correctly, they should be in the same div as the body text, which is created in `Xml2Html.hs`.  The footer is easy, titles are harder, but I think both suggest some rethinking of the interaction between hakyll and `Xml2Html.hs`.

My inclination is to merge this, put out the new website, and sort out these issues at a later date.