Added Schedules endpoint that returns a plaintext iCal file.

Changed front end from downloading an iCal file to opening a webcal://
link.

this was much less work than I expected
2 jobs for 19-webcal in 2 minutes (queued for 1 second)
Name Stage Failure
failed
test_api Test


bin/rails test test/controllers/schedules_controller_test.rb:4

.......

Finished in 0.781416s, 20.4756 runs/s, 26.8743 assertions/s.
16 runs, 21 assertions, 1 failures, 0 errors, 0 skips
ERROR: Job failed: exit code 1