[CalDAV] Add workaround for FastMail servers
[CalDAV] Add workaround for FastMail servers

The FastMail doesn't advertise PUT on collections, which is used
for write access checking. Let's add POST as an alternative, to
have FastMail calendars writeable.

tintou/evolution-data-server,tintou/evolution-data-server,matzipan/evolution-data-server,tintou/evolution-data-server,tintou/evolution-data-server,matzipan/evolution-data-server,matzipan/evolution-data-server,matzipan/evolution-data-server,matzipan/evolution-data-server