Added Multi-level subdomain wildcard

[YPetremann]

.example.com would match www.example.com sub.sub.sub.example.com www..example.com would match www.example.com www.sub.sub.example.com but not sub.sub.example.com

[dougwilson]

Thanks for the pull request! Unfortunately I'm going to decline, because this goes beyond the design goals of this module. The string syntax is meant to match SSL certificates CN syntax. Anything beyond that, this module already accepts a regexp as well, which will allow you to use anything you want 😲