Need incremental iCalendar parsing to avoid blocking

[dreid@…]

http_PUT blocks while storing the calendar data, and it can take up to 5 minutes for a request involving a 208K ics file to complete. This is obviously a pretty good place for a DoS to happen. I suspect the culprit is the calendar validation, this stuff should be deferred to a thread.

Note we have a similar problem with XML; we probably need to switch to ElementTree or similar.

[wsanchez@…]

Ew, yes.

[wsanchez@…]

We're going to need an iCalendar parser that can do incremental parsing, which means adding that capability to vobject. Not sure how much work that's going to be...

[wsanchez@…]

See #16