Add 404 page
Add 404 page

We could use a better one, but this will do for now.

Closes #25

djds23/pygotham-1,PyGotham/pygotham,pathunstrom/pygotham,djds23/pygotham-1,PyGotham/pygotham,pathunstrom/pygotham,pathunstrom/pygotham,PyGotham/pygotham,PyGotham/pygotham,pathunstrom/pygotham,djds23/pygotham-1,pathunstrom/pygotham,djds23/pygotham-1,PyGotham/pygotham,djds23/pygotham-1