Clone of https://issues.kolab.org/show_bug.cgi?id=5067
The [[http://busymac.com/busycal/index.html | BusyCal]] calendaring app apparently uses the `COMPLETED` property for flagging tasks as complete. This doesn't sync to Kolab and leads to tasks marked as complete in BusyCal not being set as complete in the backend and also tasks with status:complete from the web client still appearing incomplete in BusyCal.
COMPLETED is defined in RFC 5545 Section 3.8.2.1 and holds a UTC timestamp:
COMPLETED:20150527T100222Z
Steps to reproduce and test:
# Create two tasks "A" and "B" in the web client
# Sync tasks with BusyCal via CalDAV
# Mark task "A" as complete in the web client
# Mark task "B" as complete in BusyCal
# Sync tasks with BusyCal
Expected results:
- Task "A" appears as complete in BusyCal
- Task "B" appear as complete in the web client