Iterate over all the pois and add them to the map

* First we create the map
* If the browser supports geoloaction, we center the map on the user location
* For each poi we create:
  - A new marker with the poi name. We use the poi id as part of the javascript variable name.
  - A new info window with the poi description as the content. We use again the poi id as part of the javascript variable name.
  - A new event to the marker, when you click it, we will open the info window associated to it.