the DST change on pull 17 cause some new error

[cshiong]

on this commit, I found a new error.
seems all the job scheduled on DST day will be scheduled at 3am (fall early). i assume it should be just that missing our jobs fall to early time.
e.g
schedule: 0 14 * * * * timezone: America/Los_Angeles fromTime: 2016-03-12 14:01:00 -0800 PST
reschedule to: 2016-03-13T03:00:00-07:00
in the master version, it is set correct to 2016-03-13T14:00:00-07:00