Fix crontab parsing

REF #124
Sure!

> On Dec 28, 2557 BE, at 7:34 PM, Rob Emery <notifications@github.com> wrote:
> 
> In t/ParseCron.t <https://github.com/duckduckgo/zeroclickinfo-goodies/pull/882#discussion-diff-22297725>:
> 
> > @@ -14,6 +14,8 @@ ddg_goodie_test(
> >  	)],
> >  	'crontab * */3 * * *' => test_zci(qr/^Cron will schedule the job at this frequency:\s*\n\s*\d{1,2}:\d{1,2}:\d{1,2} on \d{1,2} [a-zA-Z]{3}, \d{4}\s*\n\s*\d{1,2}:\d{1,2}:\d{1,2} on \d{1,2} [a-zA-Z]{3}, \d{4}\s*\n\s*\d{1,2}:\d{1,2}:\d{1,2} on \d{1,2} [a-zA-Z]{3}, \d{4}$/),
> >  	'crontab 42 12 3 Feb Sat' => test_zci(qr/^Cron will schedule the job at this frequency:\s*\n\s*\d{1,2}:\d{1,2}:\d{1,2} on \d{1,2} [a-zA-Z]{3}, \d{4}\s*\n\s*\d{1,2}:\d{1,2}:\d{1,2} on \d{1,2} [a-zA-Z]{3}, \d{4}\s*\n\s*\d{1,2}:\d{1,2}:\d{1,2} on \d{1,2} [a-zA-Z]{3}, \d{4}$/),
> > +	'crontab 42 12 3 feb sat' => test_zci(qr/^Cron will schedule the job at this frequency:\s*\n\s*\d{1,2}:\d{1,2}:\d{1,2} on \d{1,2} [a-zA-Z]{3}, \d{4}\s*\n\s*\d{1,2}:\d{1,2}:\d{1,2} on \d{1,2} [a-zA-Z]{3}, \d{4}\s*\n\s*\d{1,2}:\d{1,2}:\d{1,2} on \d{1,2} [a-zA-Z]{3}, \d{4}$/),
> > +	'crontab 42 12 3 * sat' => test_zci(qr/^Cron will schedule the job at this frequency:\s*\n\s*\d{1,2}:\d{1,2}:\d{1,2} on \d{1,2} [a-zA-Z]{3}, \d{4}\s*\n\s*\d{1,2}:\d{1,2}:\d{1,2} on \d{1,2} [a-zA-Z]{3}, \d{4}\s*\n\s*\d{1,2}:\d{1,2}:\d{1,2} on \d{1,2} [a-zA-Z]{3}, \d{4}$/)
> Can you improve the tests here and add some other formats like:
> 
> crontab * 0/5 * * *
> crontab 0 23 28-31 * *
> —
> Reply to this email directly or view it on GitHub <https://github.com/duckduckgo/zeroclickinfo-goodies/pull/882/files#r22297725>.
>