title: JsonConverter CanConvert does not receive type
body: <p>I have a custom <code>JsonConverter</code>, which doesn't seem to be called correctly. I have created the converter, added it to the <code>JsonSerializerSettings.Converters</code> collection and marked the property on the entity I am serialising with <code>[JsonConverter(typeof(SearchGeoConverter))]</code>, but even with these in place the converters <code>CanConvert</code> method never sees the type I am trying to convert. I only ever see, <code>string</code>, <code>int</code> and <code>JObject</code>.</p>
  
  <p>My converter looks like this:</p>
  
  <pre><code>public class SearchGeoConverter : JsonConverter
  {
      public override bool CanConvert(Type objectType)
      {
          return typeof(DbGeography).IsAssignableFrom(objectType);
      }
  
      public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
      {
          var point = (DbGeography) value;
          var rawJson = string.Format("{{ \"type\": \"Point\", \"coordinates\": [{0}, {1}] }}", point.Latitude, point.Longitude);
          writer.WriteRaw(rawJson);
      }
  
      public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
      {
          throw new NotImplementedException();
      }
  }
  </code></pre>
  
  <p>What am I missing?</p>