About no_local: true validation complexity

[aviscasillas]

Hi guys,

I'm currently having to deal with url validation in our ActiveRecord models and I found this gem that feels a useful one to encapsulate that functionality.

Btw, I've just realised that the validation for no_local url's is quite simple as it just checks that the host contains a ., but it doesn't really care about aspects like the position of the dot, or the existence of www.

So it considers following urls as valid ones:
http://.whatever
http://www.

Is there any reason for that?
Would you accept a PR with extra checks?

Cheers!