Crontab linter.

chkcrontab.py is a script to check crontab files like those in
/etc/cron.d and /etc/crontab.  It tries to catch glaring errors
and warn on suspect lines in a crontab file.  Some valid lines
will generate warnings.  Certain silly yet valid crontab lines
will generate errors as well.

Run this by doing ./chkcrontab.py crontab_file

Errors will cause a non-zero exit code.  Warnings alone will not.

To see sample output for a bad crontab, run the following:

  ./chkcrontab.py ./tests/test_crontab

See the ./tests/test_crontab.disable crontab for how to disable
warnings and errors.

CONTRIBUTIONS

Please add unit tests for new features or bug fixes.  To run all
the unitests run ./setup test.
