fix bug when attribute logfile is nil
Chef::ShellOut is deprecated, please use Mixlib::ShellOut
import cron cookbook from https://github.com/opscode-cookbooks/cron/tree/ff7d5041449845aa73a7910413450e3ec3a478a1 and add template to manage users' cron jobs
Merge pull request #154 from phunehehe/redisio

fix bug when attribute logfile is nil
Merge pull request #155 from phunehehe/cron

add cron cookbook