Add 'CableTypes' (#406)

* Move relevant fields and create migration to autogen cable types

* CRUD and ordering

* FIX: Prevent creating duplicate cable types

* FIX: pep8/remove debug print

* FIX: Meta migrations... :>

* FIX: Update tests to match new UX

* Move cabletype menu links into 'Assets' dropdown

* Fix migration

* Specify version of reportlab

Should fix CI - looks like I went a bit too ham-handed in my requirements.txt purge last time...

assets/migrations/0012_auto_20200218_1627.py

@@ -0,0 +1,26 @@
+# Generated by Django 2.0.13 on 2020-02-18 16:27
+
+from django.db import migrations
+from django.db.models import Q
+
+
+def move_cable_type_data(apps, schema_editor):
+    Asset = apps.get_model('assets', 'Asset')
+    CableType = apps.get_model('assets', 'CableType')
+    for asset in Asset.objects.filter(is_cable=True):
+        # Only create one type per...well...type
+        if(not CableType.objects.filter(Q(plug=asset.plug) & Q(socket=asset.socket))):
+            cabletype = CableType.objects.create(plug=asset.plug, socket=asset.socket, circuits=asset.circuits, cores=asset.cores)
+            asset.save()
+            cabletype.save()
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('assets', '0011_auto_20200218_1617'),
+    ]
+
+    operations = [
+        migrations.RunPython(move_cable_type_data)
+    ]