queryMany-batch returns hit list

Query many now returns a hit list. Each item in the hit list corresponds to the latlng requested and contains a list of features corresponding to that latlng and also it's distance to the feature.

Example:

```
{
 hits: {
   1: [ {feature_id:1,distance:0.1}, {feature_id:2,distance:10]},
   ....
 },
 features: {
   1: <feature>,
   2: <another feature>,
   ...
 }
}
```

Known issue: The hit list returns key values as strings versus number (known issue, [ref](http://jayconrod.com/posts/52/a-tour-of-v8-object-representation)).

cc @springmeyer @yhahn