**Bug fixes**
- Flushing a server no longer breaks migration of the storage backend
(1460). If you have ever flushed a server in the past, migration
may be broken. This version of Kinto tries to guess what version of
the schema you're running, but may guess wrong. See
https://github.com/Kinto/kinto/wiki/Schema-versions for some
additional information.
**Internal changes**
- We now allow migration of the permission backend's schema.
**Operational concerns**
- *The schema for the Postgres permission backend has changed.* This
changes another ID column to use the "C" collation, which should
speed up the `delete_object_permissions` query when deleting a
bucket.