us-map on index page

display location of all byways
clicking on a byways marker takes you to a byway page
us map color markers

byway markers have colors based on the byway type
map styles added to switch off some of the map features
Default styling for borders and state names
Display other byways on main map
Display byways on map in the vertical order (z-index) determined by position of byway designation
Byway map colors in agreement with managing agency emblems
Remove unused style for borders
Render byway path info in HTML
display byway routes on the state maps

polyline display is triggered by the presence of data-path element in
byway link
Merge remote-tracking branch 'origin/maps'