CMS Ad-Ops Calendar import script

[svevang]

Create a script to generate/parse the current Ad-Ops working calendar for all important shows and import that cal data into the managed calendar set up in PRX/cms.prx.org#516

Once backfilled, augury can start "dog-fooding" the official calendar API across in augury: https://github.com/PRX/augury/issues/1

As a CI data process, this script should be able to be run regularly (idempotent).