title: withinkilometers geoquery in parse cloud fails with MongoDB error
body: <p>I'm trying to get the closest Parse Object that is within 20 kms of a location.</p>
  
  <pre><code>  var testPoint = new Parse.GeoPoint({latitude: fromLatLng.lat, longitude: fromLatLng.lng});
    var BKcity = Parse.Object.extend("BKcity");
    var cityQuery = new Parse.Query(BKcity);
    //Throws mongo error
    cityQuery.withinKilometers("location", testPoint, 20);
    cityQuery.find({
    ...
  </code></pre>
  
  <p>However query fails with:</p>
  
  <pre><code>�[31merror�[39m: Uncaught internal server error. { [MongoError: Can't canonicalize query: BadValue geo near accepts just one argument when querying for a GeoJSON point. Extra field found: $maxDistance: 0.003139224611520954]
        name: 'MongoError',
        message: 'Can\'t canonicalize query: BadValue geo near accepts just one argument when querying for a GeoJSON point. Extra field found: $maxDistance: 0.003139224611520954',
        '$err': 'Can\'t canonicalize query: BadValue geo near accepts just one argument when querying for a GeoJSON point. Extra field found: $maxDistance: 0.003139224611520954',
        code: 17287 } MongoError: Can't canonicalize query: BadValue geo near accepts just one argument when querying for a GeoJSON point. Extra field found: $maxDistance: 0.003139224611520954
          at Function.MongoError.create (D:\home\site\wwwroot\node_modules\mongodb-core\lib\error.js:31:11)
          at queryCallback (D:\home\site\wwwroot\node_modules\mongodb-core\lib\cursor.js:182:34)
          at Callbacks.emit (D:\home\site\wwwroot\node_modules\mongodb-core\lib\topologies\server.js:119:3)
          at null.messageHandler (D:\home\site\wwwroot\node_modules\mongodb-core\lib\topologies\server.js:295:23)
          at Socket.&lt;anonymous&gt; (D:\home\site\wwwroot\node_modules\mongodb-core\lib\connection\connection.js:285:22)
          at emitOne (events.js:77:13)
          at Socket.emit (events.js:169:7)
          at readableAddChunk (_stream_readable.js:146:16)
          at Socket.Readable.push (_stream_readable.js:110:10)
          at TCP.onread (net.js:523:20)
  </code></pre>
  
  <p>Query works on javascript, .near() query also works but not withinKilometers query. </p>
  
  <p>Is this a parse-server bug or mlab issue or a silly mistake on my part?</p>