Providing {:type => :usa_ssn} is deprecated and will be removed in the future. Please use `:ssn => true` instead.

I made `{:type => :usa_ssn}` deprecated for SSN validation, because such additional logic is overhead because I don't know countries with same identification name (ssn). I think that we need to have this deprecation message at least for one release and then I'll finally remove the code which'll make code cleaner.