Use Kwi\UrlLinker to link both URLs and emails.

[drifteaur]

See https://bitbucket.org/kwi/urllinker. Needs composer to install the dependency.

[mattstauffer]

So, one year late.. I have this tendency of not getting my GitHub notifications for some reason. Drives me nuts.

Thanks for this PR! I want to make this still work for people who don't use Composer, so maybe it's worth tweaking this a bit so that, if the person hasn't run composer install and tries to use auto_link, it dies with a simple notification or something. I'll take a look later but if you @drifteaur or anyone else wants to update this PR to do that, that would be awesome too.