Change foreign keys to TreeForeignKey

InvenTree/stock/migrations/0013_auto_20190908_0916.py

@@ -0,0 +1,20 @@
+# Generated by Django 2.2.5 on 2019-09-08 09:16
+
+from django.db import migrations
+import django.db.models.deletion
+import mptt.fields
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('stock', '0012_auto_20190908_0405'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='stockitem',
+            name='location',
+            field=mptt.fields.TreeForeignKey(blank=True, help_text='Where is this stock item located?', null=True, on_delete=django.db.models.deletion.DO_NOTHING, related_name='stock_items', to='stock.StockLocation'),
+        ),
+    ]

InvenTree/stock/migrations/0014_auto_20190908_0918.py

@@ -0,0 +1,20 @@
+# Generated by Django 2.2.5 on 2019-09-08 09:18
+
+from django.db import migrations
+import django.db.models.deletion
+import mptt.fields
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('stock', '0013_auto_20190908_0916'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='stocklocation',
+            name='parent',
+            field=mptt.fields.TreeForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.DO_NOTHING, related_name='children', to='stock.StockLocation'),
+        ),
+    ]