Update status codes (#307)

* Extra error info when connecting to server

* Adds accessors for various types of status codes

* Cleanup / refactor stock status codes

- No longer need to duplicate these on the app

* improvements to purchase order list

- Add option to show closed orders
- Render order status

* Add purchase order status to order detail widget

* Update release notes

* Cleanup for imports

* linting fixes

lib/widget/stock_item_history.dart

@@ -33,7 +33,7 @@ class _StockItemHistoryDisplayState extends RefreshableState<StockItemHistoryWid
 
     history.clear();
 
-    InvenTreeStockItemHistory().list(filters: {"item": "${item.pk}"}).then((List<InvenTreeModel> results) {
+    await InvenTreeStockItemHistory().list(filters: {"item": "${item.pk}"}).then((List<InvenTreeModel> results) {
       for (var result in results) {
         if (result is InvenTreeStockItemHistory) {
           history.add(result);