Update feedzirra to prevent errors

Error messages from cron like this:

DATE CAN'T BE PARSED: 2013-02-21T11:25:00.005-08:00
DATE CAN'T BE PARSED: 2013-02-21T11:25:48.391-08:00
DATE CAN'T BE PARSED: 2013-02-19T16:47:00.001-08:00
DATE CAN'T BE PARSED: 2013-02-20T10:23:03.888-08:00
DATE CAN'T BE PARSED: 2013-02-19T16:37:00.003-08:00