Return status and output from job

- To see what actually happened
Clear caches after updating jobs
Cleaned up cache clearing script

- Make it easier to add more hosts
- Don't use a temp variable for the URL; unnecessary
Merge branch 'hotfix/comics-job-output'

Attempt to make the comic cronjob more robust:
- Send output so that I can inspect it later
- Emit a cache-clear job from both comics and github-fetch jobs on completion