Added xs-viewport column sizes for header and navs
Added xs-viewport column sizes for header and navs

Added `col-xs-#` classes to the header and nav button containers to prevent overlapping on extra-small (phone) screens.
mkalish/clean-slate,oehokie/clean-slate,RyanGladstone/clean-slate,FairfaxRuby/clean-slate,jrleszcz/clean-slate,ParentJA/clean-slate,omarimayerswalker/clean-slate,rdeprey/clean-slate,RyanGladstone/clean-slate,oehokie/clean-slate,jrleszcz/clean-slate,MissionLaunch/clean-slate,DavidGinzberg/clean-slate,codefordc/clean-slate,MissionLaunch/clean-slate,phantomhaircuts/clean-slate,DavidGinzberg/clean-slate,omarimayerswalker/clean-slate,rdeprey/clean-slate,ParentJA/clean-slate,codefordc/clean-slate,mkalish/clean-slate,FairfaxRuby/clean-slate,phantomhaircuts/clean-slate