URL validation fails for valid domain

[little-dude]

Hi,

Thanks for this library. I'm running into an issue where the url validator rejects a valid URL:

>>> import validators      
>>> validators.url("http://my-service:5000") 
ValidationFailure(func=url, args={'value': 'http://my-service:5000', 'public': False})

[ramiroestrada]

Seems to fail if here is no fully qualified name:

>>> validators.url("http://my-service:5000") 
ValidationFailure(func=url, args={'value': 'http://my-service:5000', 'public': False})
>>> validators.url("http://my-service.com:5000") 
True
>>> 

[InnovativeInventor]

There is an option for a whitelist in validators.email, I believe. That could also be re-implemented in validators.url.