Delete all batches before adding new ones.
The SwitchHistoricalJob supports two search modes.

* Provide a switch id and the job will search only one switch's
  records.
* With no switch id provided, all switches will have their
  records searched.
Switches now can handle self-queueing.
When a new switch is added, its records will be searched.
Turn on dynamic scheduling.
Switch to cron scheduling.
The Switch model takes care of queuing up its own jobs.
Made internal methods private.
Adding a rake task to reload switch schedules.
Reload switch schedules during application start.