title: Leaflet Draw not taking properties when converting FeatureGroup to GeoJson
body: <p>I'm unable to convert my Layer properties into the properties of the GEOJson object using Leaflet(0.7.7)/Leaflet.Draw(latest). My workflow is:</p>
  
  <p>1 Create Map: <code>var map = L.map('#map', options);</code></p>
  
  <p>2 Create a FeatureGroup: <code>features= new L.FeatureGroup();</code></p>
  
  <p>3 Add to the Leaflet Map:  <code>map.addLayer(features);</code></p>
  
  <p>4 On the <code>draw:created</code> event, I'm capturing <code>e.layer</code> and adding a bunch of properties:</p>
  
  <p><code>var layer = e.layer;</code></p>
  
  <p><code>layer.properties = { Title: 'Hello' };</code></p>
  
  <p><code>features.addLayer(layer);</code></p>
  
  <p><code>geo_features = features.toGeoJSON();</code></p>
  
  <p>However, my <code>geo_features</code> always have empty property attributes in each of the features and I can't figure it out!</p>