Brad King cb27cfb1cc Use human-readable Git commit times in Update.xml
Previously we produced commit times formatted like

  1261403774 -0500

which is what the Git plumbing prints.  Now we use a human-readable
format like

  2009-12-21 15:28:06 -0500

which is still easy to machine-parse.
2009-12-21 10:29:00 -05:00
..
2009-12-20 23:53:43 -05:00
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2009-12-08 09:38:36 -05:00
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