Per airbnb request, use a separate json field for time zone

Also updated to a current version of scala
Given this has a default value it would be better to move it down with the other properties with default values.  This will keep the use site consistent when not wanting to specify the `scheduleTimeZone`.  By doing this  the usage scenario when the `scheduleTimeZone` is not specified can be written as `ScheduleBasedJob("R/2014-10-10T18:32:00Z/PT60M", "cool-job", "echo coolness")` instead of `ScheduleBasedJob("R/2014-10-10T18:32:00Z/PT60M", "", "cool-job", "echo coolness")`.  Then when `scheduleTimeZone` needs to be specified its explicit `ScheduleBasedJob("R/2014-10-10T18:32:00Z/PT60M", "cool-job", "echo coolness", scheduleTimeZone = "PST")`.

This will help to cleanup all the use sites that had be changed in the tests even though no new values/parameters are being passed.