Support kwargs for validators

[theteladras]

The idea would be to have the validator functions, which accept an dict options argument, to also support a variant of the methods that can accept options via kwargs.

For example the is_email validator, accepts as a second argument an options dict, like in this case:

is_email("some@value.py", { "allow_display_name": True })

The idea would be to have this method also accept kwargs with the same option properties with a lower precedence over the dict argument.

So the execution of the validator would end up something like this:

is_email("some@value.py", allow_display_name=True)