Add feature that shows cron format as friendly string

[Marak]

As suggested by http://reddit.com/u/HereComeTheMinions http://www.reddit.com/r/programming/comments/2ma95k/visual_opensource_cron_editor/cm2cxpa

Provide friendly text format explaining cron, such as:

*/20 * * 13,12,24 8,11 *
# Every twenty seconds on on the 12th, 13th and 24th, only in august and november.

+30 Internet Points

[lipangit]

Come on, I support you

[GDmac]

6½ years later... like azza-bazoo.github.io/prettycron/