Model.all returns multiple instances of the same object when using association eager loading

Association eager loading may create multiple instances of parent object because result set rows are not sorted by parent object id.
I actually got something like this:
```coffeescript
geddy.model.DbConfig.all {}, {includes: ['db_connections']}, (err, dbConfigs) =>
  dbConfigs[0].id #=> "FOO123"
  dbConfigs[1].id #=> "BAR456"
  dbConfigs[2].id #=> "FOO123"   (duplicate object!)
```
And db_connections association objects were split in two halfs between this two copies of parent object.