0.4.0

New features

• Previous files can be kept if the setting kinto.keep_old_files is set
  to true. This can be useful when clients try to download files from a
  collection of records that is not up-to-date.
• Add heartbeat entry for attachments backend (#41)

Bug fixes

• Now compatible with the default bucket (#42)
• Now compatible with Python 3 (#44)

Internal changes

• Upload/Download scripts now use kinto.py (#38)