Output times in UTC.

Let the client localize the times with js/local-time.js themselves. No
one cares what the server timezone is.

This fixes a bug where posts made in a different daylight savings mode
have their times displayed off by an hour. Their times would be rendered
to the server's own timezone area correctly, but then the server's
*current* utc-offset would be appended, which wouldn't match up.
Merge pull request #113 from Macil/tzfix

Output times in UTC