fix(layer): This suscribe was not referencing to named id (#113)

* This suscribe was not referencing to named id

This suscribe was not using the named id as defined into the context.json

* lint error

src/lib/context/shared/layer-context.directive.ts

@@ -68,7 +68,9 @@ export class LayerContextDirective implements OnInit, OnDestroy {
     this.dataSourceService
       .createAsyncDataSource(dataSourceContext)
       .subscribe(dataSource =>  {
-        this.getLayerParamVisibilityUrl(dataSource.id, layerContext);
+        this.getLayerParamVisibilityUrl(
+          dataSource.options['id'] ?
+          dataSource.options['id'] : dataSource.id  , layerContext);
         this.map.addLayer(
           this.layerService.createLayer(dataSource, layerContext));
       });