0.4.0

• #472: If you were using Sqlite, Cal- CardDAV clients might have missed
  updates from the server.
• #482 / #490: Fix installation issue if Sqlite is not enabled. (@fabianwolf)
• #491: Added CalDAV Scheduling plugin.
• Added Property Storage plugin.
• Removed features related to locking the admin interface. This means that you
  no longer have to create the ENABLE_ADMIN / ENABLE_INSTALL files.
• Ships with sabre/dav 3.1.2