Use the much fancier url-regex

Scraps the existing regex in favor of https://github.com/kevva/url-regex, per @sindresorhus's suggestion. Because the new regex is more permissive, schemeless strings like `google.com` are considered to be URLS. This is a breaking change, so I'm thinking of shipping this as 2.0.0.
I'm -1 on this change in that case, purely because we use this in places that users enter a "URL", like to associate with their project, or their development environment (eg. imagine when signing up for an analytics tool and creating a project).

I can see how you might disagree, but in that case feel free to just use the `url-regex` module directly. This one is doing what we want it to do just fine for us right now.