Merge pull request #2 from fma2/mapbox

Implement Mapbox - replacing the Google Maps API
Comment out place markers for individual markers, add loader
Add styling for loader
Add markerclusterer markers via mapbox geojson - rather than through low level leaflet
Add method to filter markers in markerclusterer with checkbox on school type
Remove commented out code that created marker clustering via leaflet - low-level marker clusters
Remove commented out code that placed individual markers on map with popup via mapbox geojson
Remove code that filtered markers by using divs - on link click
Change menu-ui nav from just links to a list of links within ul-li structure, add filters nav element
minor indent mods, add styling for filters div
Remove list items that were being used for filtering before
Remove console logs from debugging, comment out line of code that immediately places all items on map
Add li div to be appended to filters div