Configuration file driven testing schedule

[theurich]

Mark and I discussed this during the ESMF core call today. It would be very convenient to have all testing platforms on a 15min (or so) heartbeat, probably implemented via cron, to pull from the esmf-test-scripts repo. Introduce a configuration file under the esmf-test-scripts repo that specifies at what time(s) a specific platform starts its automated testing.
This approach allows everyone to easily see on what schedule our nightly tests are currently running. Secondly, developers can very easily modify the schedule without needing machine access. This can come in handy when needing to quickly test something across a set of platforms.

[ryanlong1004]

@theurich I think the easiest solution would be to allow anyone to drop a "run_" file in the config folder and push to the repo.

We'll have a cron job setup to look for a "run_" every 15 mins and trigger the start, then will remove the file so it's not re-run.

[theurich]

Still an interesting idea. For now just relying on the nightly crontab seems sufficient. Maybe in the future we want to build this out, especially if we need more control of parts of the testing. E.g. we might want to run esmf-extended-tests, and specifically BFB testing on a less frequent basis.