Allow PartCategory and StocKLocation names to be non-unique

- As long as they are unique in the current tree level

InvenTree/part/migrations/0027_auto_20200202_1024.py

@@ -0,0 +1,19 @@
+# Generated by Django 2.2.9 on 2020-02-02 10:24
+
+import InvenTree.validators
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('part', '0026_auto_20200131_1022'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='partcategory',
+            name='name',
+            field=models.CharField(max_length=100, validators=[InvenTree.validators.validate_tree_name]),
+        ),
+    ]