2.5-based build running at Fastmail

[Bron Gondwana]

In really excellent news, I have a version of FastMail's code all rebased on top of the current master branch now running for about 2% of users since last night.  No bug reports yet - and all our staff are in that 2% :)

I'm planning to push this to the rest of our users over the next few days.

I added versioning and upgrade logic to the caldav db rather than having to dav_reconstruct during the upgrade.  It's still a good idea to do a dav_reconstruct of course, because it picks up the status field then.

I will need to pick through the fixes I had to make and figure out which ones belong in upstream.

The only big-ticket thing missing for 2.5 is replication protocol tidying and support for annotation.  Of course there are probably still bugs, but at least having it running in production means it's being hammered more.

Bron.

-- 
  Bron Gondwana
  brong at fastmail.fm