Added markdown to running notes generated after 2014-12-18

Will update date to 2015-01-01 when we go live on production.
I'm not aware of it within Tornado in a useful form (I think it has methods to return an entire HTML page, but we want to make that ourselves so that it has the navigation and so on).

Is there anywhere more top level to have this? This is the main error handler used for the whole site, so it's only executed when an error is triggered, and all errors in all pages use this code..

More helpful messages would be nice, but as it's used by lots of different pages, I guess the reasons for say, a 404, could differ. Happy for suggestions though.