createMap(mapType) {
    var mapOptions = {
      backgroundColor: '#000000',
      center: trendy.App.DEFAULT_CENTER,
      disableDefaultUI: true,
      zoom: trendy.App.DEFAULT_ZOOM
    };
    var mapEl = $('.map').get(0);
    var map = new google.maps.Map(mapEl, mapOptions);
    map.setOptions({styles: trendy.App.BLACK_BASE_MAP_STYLES});
    map.overlayMapTypes.push(mapType);
    return map;
  }
Creates a Google Map with a black background the given map type rendered.
The map is anchored to the DOM element with the CSS class 'map'.
@param {google.maps.ImageMapType} mapType The map type to include on the
    map.
@return {google.maps.Map} A map instance with the map type rendered.