Adding Footprints Controller

FootprintsController added. Now able to perform a GET request to grab layer features within a specified bbox.

GET request format:
/api/footprints/<workspace>?bbox=minx,miny,maxx,maxy

Returns GeoJSON for all features contained in all layers in the specified <workspace> intersecting with the specified bbox. If no bbox parameter is specified or it is malformed, the entire layer is used.