extend regex to support keys that contain "_" or "-"
--
e.g.: https://docs.google.com/spreadsheets/d/1vXqouursElZIEhxBK_BlqcXUjIyKJg5FWIHU-kDayiM/edit#gid=0
Merge pull request #3 from preciousforever/master

Support URLs where key contains "_" underscore and "-" dash characters