fix for get_crontab(), now returns all crontabs instead of the last crontab returned from 'sudo crontab -u <user> -l'
catching up to master
removing duplicate from merge conflict
that merge conflict was needlessly difficult..
refactor of get_crontab() to use cron command as a hash key instead of logical order integer
implemented validate_cron() method
unit tests for validate_cron()
Merge pull request #64 from avaghti1/master

refactor of get_crontab() & implementation of validate_cron()