abstract cron functionality for unix.
abstract cron entry creation and reset @cron_exists on load.
add aix cron provider mapping.
fix cron unit test, this worked since @cron_exists was not reset properly.
move tests to abstracted unix cron.
cron functional tests.
popen4 can yield while child has already died.
exclude cron attributes test for solaris.
add solaris platform list.
add all solaris platforms.
run cron functional test only for root.
solaris9, 10 on some failures for example invalid mins in crontab fails with exit code of zero
fix unit test for cron and stderrs check nil.