Rename Part.URL -> part.link

- Previous migration needed some tweaking to get it to run... because.. why?
- It seems to pass when running manage.py migrate but fails when running manage.py test
- Stumped on this one

InvenTree/part/migrations/0034_auto_20200404_1238.py

@@ -1,6 +1,7 @@
 # Generated by Django 2.2.10 on 2020-04-04 12:38
 
 from django.db import migrations
+from django.db.utils import OperationalError
 
 from part.models import Part
 from stdimage.utils import render_variations
@@ -11,11 +12,13 @@ def create_thumbnails(apps, schema_editor):
     Create thumbnails for all existing Part images.
     """
 
-    for part in Part.objects.all():
-        # Render thumbnail for each existing Part 
-        if part.image:
-            part.image.render_variations()
-
+    try:
+        for part in Part.objects.all():
+            # Render thumbnail for each existing Part 
+            if part.image:
+                part.image.render_variations()
+    except OperationalError:
+        print("Error - could not generate Part thumbnails")
 
 class Migration(migrations.Migration):
 

InvenTree/part/migrations/0035_auto_20200406_0045.py

@@ -0,0 +1,18 @@
+# Generated by Django 2.2.10 on 2020-04-06 00:45
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('part', '0034_auto_20200404_1238'),
+    ]
+
+    operations = [
+        migrations.RenameField(
+            model_name='part',
+            old_name='URL',
+            new_name='link',
+        ),
+    ]