COUCHDB-627 - Support all timezones

Forward-ported over top of MochiWeb 2.4.2, comprising specific chunks
of b1a049bb, 445e919, 010522e, 317c97f lost during MochiWeb upgrade.

Some timezones are incorrectly handled by OTP's calendar module. The
ironic thing is that we only ever need the time in GMT (for HTTP
response headers and the log file).

This patch duplicates httpd_util:rfc1123_date/0 and /1 but uses
universal time everywhere, avoiding the broken conversion code.

- Support all timezones for R14 series.
- the _dst variant does exist in R14B04.
- Fix local to universal handling.

Also relates to COUCHDB-1513, a duplicate of COUCHDB-627.