ActivityLog deletions should cascade from user.

migrations/108-log-cascade.sql

@@ -0,0 +1,8 @@
+ALTER TABLE `log_activity` DROP FOREIGN KEY `user_id_refs_id_3fa7a30a`;
+
+ALTER TABLE `log_activity`
+    ADD CONSTRAINT `user_id_refs_id_3fa7a30a`
+        FOREIGN KEY `user_id_refs_id_3fa7a30a` (`user_id`)
+        REFERENCES `users` (`id`)
+        ON DELETE CASCADE;
+