Added a category index, minor fixes to code and added a
test post
Added a message on post excerpts
Added links to sidebar, trying to get tutorials the way i'd like
them. For now, they work well with exporting from ipython,
but the syntax highlighter that's included in blogofile is not
as nice as the ipython one ... Would also need to write up an
automatic way for every .md to get it's own .html