Autogenerate Jacks context

[tcmitchell]

The Jacks context should be generated via a cron job. There should be a mechanism for keeping the last few Jacks contexts in case it needs to be reverted.

This would require a geni-lib installation. See https://github.com/GENI-NSF/geni-portal/wiki/Jacks-Context for more info about installing geni-lib dependencies and running the Jacks context generation software.