Configuration/settings files2

I thought it would be time to advance the yesod version a bit.
 - Updated to pandoc 1.13
 - removed the manual opening of socket. (I was not sure if you wanted to use it, so if you prefer to keep it, I can modify the PR)
 - added a command line interface like in gitit v1 (and mostly copied from there)
 - changed the link to static resources to `/static` instead of `http://mydomain/static` as it does not play well in a https reverse proxy