Add option to disable matching urls with http basic authentication

[sseppola]

Fixes #51 by adding an option to disable the HTTP Basic Authentication regex that matches on emails.

It's worth noting that without the exact option the regex will match:
[email protected] -> github.com
http://[email protected] -> github.com

I'm not familiar enough with regex to thinker with the pattern to make it reject urls with @ in it.

[niftylettuce]

This issue is fixed in my maintained and modern version of this package at https://github.com/niftylettuce/url-regex-safe. You should be able to switch from url-regex to url-regex-safe now. See the updated list of options as I added some new ones, and changed a few defaults to more sensible ones (since not everyone is parsing Markdown for instance).