Add endpoint for StockLocation model

lib/inventree/stock.dart

@@ -19,4 +19,25 @@ class InvenTreeStockItem extends InvenTreeModel {
 
     return item;
   }
+}
+
+
+class InvenTreeStockLocation extends InvenTreeModel {
+  @override
+  String URL = "stock/location/";
+
+  InvenTreeStockLocation() : super();
+
+  InvenTreeStockLocation.fromJson(Map<String, dynamic> json) : super.fromJson(json) {
+
+  }
+
+  @override
+  InvenTreeModel createFromJson(Map<String, dynamic> json) {
+
+    var loc = InvenTreeStockLocation.fromJson(json);
+
+    return loc;
+
+  }
 }