Merge pull request #15 from a-detiste/master

move man page to section 8
Merge pull request #16 from a-detiste/master

make cron-update.(path,service) static
Merge pull request #17 from a-detiste/master

make Persistent=true smarter
Merge branch 'master' of https://github.com/kstep/systemd-crontab-generator
add command parser