add django backend in /core

ported from laravel in c3lf/lfbackend repo

core/inventory/admin.py

@@ -0,0 +1,24 @@
+from django.contrib import admin
+
+from inventory.models import Item, Container, Event
+
+
+class ItemAdmin(admin.ModelAdmin):
+    pass
+
+
+admin.site.register(Item, ItemAdmin)
+
+
+class ContainerAdmin(admin.ModelAdmin):
+    pass
+
+
+admin.site.register(Container, ContainerAdmin)
+
+
+class EventAdmin(admin.ModelAdmin):
+    pass
+
+
+admin.site.register(Event, EventAdmin)