Support skips with hash syntax.
hudson.scheduler.BaseParser.hash=true by default: @daily should not necessarily mean 12:00 AM.
Merge branch 'master' into cron-hash-JENKINS-17311
Merge branch 'master' into cron-hash-JENKINS-17311
Promote use of crontab hashes in documentation and form validation.
introduced a constant since H/1 really doesn't mean H.
minor touch-up and documentation

as I was playing with it to understand what those logics mean.
marking the release
Merge branch 'pull-743'