Begin to add views for part models

- List BOM items
- Show category listing as linked items
- Fix some pathing issues with InvenTreeTree class

InvenTree/stock/admin.py

@@ -5,7 +5,7 @@ from .models import StockLocation, StockItem
 
 
 class LocationAdmin(admin.ModelAdmin):
-    list_display = ('name', 'path', 'description')
+    list_display = ('name', 'pathstring', 'description')
 
 
 class StockItemAdmin(SimpleHistoryAdmin):

InvenTree/stock/serializers.py

@@ -48,4 +48,4 @@ class LocationSerializer(serializers.HyperlinkedModelSerializer):
                   'name',
                   'description',
                   'parent',
-                  'path')
+                  'pathstring')