exclude non-MD files from nav bar
exclude non-MD files from nav bar

gets rid of empty space caused by stylesheet

yeungn/hackerhours.org,afeld/hackerhours.org,HackerHours/hackerhours.org,sskenner/hackerhours.org,yeungn/hackerhours.org,orta/hackerhours.org,barraponto/hackerhours.org,HackerHours/hackerhours.org,orta/hackerhours.org,barraponto/hackerhours.org,HackerHours/hackerhours.org,sskenner/hackerhours.org,afeld/hackerhours.org