`/place` queries have been executing in a way where only the ID, but not
the layer, has been considered when returning records from
Elasticsearch.
It turns out this bug was introduced almost a year and a half ago in
https://github.com/pelias/api/pull/407. A little, relatively unimportant
bit of code was looking for a property called `layers`:
```
const cmd = req.clean.ids.map( function(id) {
return {
_index: apiConfig.indexName,
_type: id.layers,
_id: id.id
};
});
```
The correct property was `layer`, so no filtering on layer was done in
the resulting [mget](https://www.elastic.co/guide/en/elasticsearch/reference/current/docs-multi-get.html) query.
There was never an acceptance test for these sorts of queries, but there
is now one in https://github.com/pelias/acceptance-tests/pull/446. The
unit tests were enforcing the incorrect behavior.
Fixes https://github.com/pelias/pelias/issues/643