title: geojson /leaflet properties issue
body: <p>im kind of new with geojson properties and leaflet js code.</p>
  
  <p>This is a very simple question, but when I make the bindpopup in my marker the title of the geojson variable disappears so I only see the html tag content but no its title.</p>
  
  <p>I wish to see in the pop up the title and under the title the popup content.</p>
  
  <p>But as I said, title disappears. Here is the code and thx for your time:)</p>
  
  <pre><code>geojson = [{
              "type": "Feature",
              "geometry": {
                "type": "Point",
                "coordinates": [data[i].longitude,data[i].latitude]
                          },
  
                  "properties": {
                  "title": "Emergencia: "+data[i].priority,
                  "icon": {
                  "iconUrl": data[i].imagen,
                  "iconSize": [50, 50], // size of the icon
                  "iconAnchor": [25, 50], // point of the icon which will correspond to marker's location
                  "popupAnchor": [0, -25], // point from which the popup should open relative to the iconAnchor
                  "className": "dot"
                          }
                          }
                  }];     //alert(data[i].longitude.valueOf());
  
                  var myLayer = L.mapbox.featureLayer().setGeoJSON(geojson).addTo(map);     
                  myLayer.on('layeradd', function(e) {
                  var marker = e.layer,
                  feature = marker.feature;
                  marker.setIcon(L.icon(feature.properties.icon));
  
                  var popupContent='&lt;br&gt;&lt;p&gt;Id emergencia:'+data[i].id_emergency+'&lt;/p&gt;'//IMPORTANTISIMO
                  marker.bindPopup(popupContent,{
                  closeButton: true,
                     minWidth: 150
                  });
  
  
                  });
                  myLayer.setGeoJSON(geojson);
  </code></pre>