We also set the initial zoom level and mapTypeId to google.maps.MapTypeId.ROADMAP. 
The following types are supported:
    * ROADMAP displays the normal, default 2D tiles of Google Maps.
    * SATELLITE displays photographic tiles.
    * HYBRID displays a mix of photographic tiles and a tile layer for prominent features (roads, city names).
    * TERRAIN displays physical relief tiles for displaying elevation and water features (mountains, rivers, etc.).

zoom levels : 
	* 0,7
	* 18.