(maint) Use 2 space tabs in cron acceptance tests
(maint) Remove cron fixtures after cron acceptance tests

Depending on the order that the cron acceptance tests ran in, fixtures
from one test could pollute the environment in another test and change
the expected output. This commit ensures that all cron acceptance tests
delete any users and crontabs as part of the cleanup phase.
Merge branch 'maint/master/acceptance-cron-acceptance-cleanup'