------------------
- Drop Plone 4.2 support. [mathias.leimgruber]
- Use E-Mail address in ics header instead of userid for the INDIVIDUAL property. [mathias.leimgruber]
- Drop Plone 4.1 support. [jone]
- An older ftw.calendar is required because of breaking changes in
https://github.com/4teamwork/ftw.calendar/pull/19 [jone]
- Replace jq with $.
[lknoepfel]