Migrate the cities map to OpenLayers3

Replace the Google map with OpenLayers3 map.
 * All participating cities are in: public/data/locations.json
 * There are two options for pins: 
   * map-pin.png (from the latest design, currently I use this one)
   * map-pin_1.png (from the old design)
 * All OpenLayers code is in public/js/map.js

*There are also some minor fixes, as using local version of jQuery, and removing reference to non-existing files.*