Fix per-layer date wrapping

lib/cartodb/models/mapconfig/adapter/vector-mapconfig-adapter.js

@@ -4,7 +4,7 @@ const dateWrapper = require('../../../utils/date-wrapper');
 /**
  * This middleware wraps the layer query transforming the date fields into numbers  because mvt tiles
  * doesnt support dates as primitive type.
- * 
+ *
  *  - This middleware is ONLY activated when the `dates_as_numbers` option is enabled for some layer in the mapConfig.
  */
 class VectorMapConfigAdapter {
@@ -28,6 +28,9 @@ class VectorMapConfigAdapter {
     }
 
     _wrapLayer(layer, user) {
+        if (!layer.options.dates_as_numbers) {
+            return Promise.resolve(layer);
+        }
         const originalQuery = layer.options.sql;
         return this._getColumns(user, originalQuery)
             .then(result => {