Fix `ruby-whois --version`

I'm using ruby-whois 3.5.5, the latest version.  But when I try to read version from CLI, it shows exceptions.

~~~
$ ruby-whois --version
~/.rvm/gems/ruby-2.1.3@sova/gems/whois-3.5.5/bin/ruby-whois:38:in `block (2 levels) in <top (required)>': uninitialized constant Whois::NAME (NameError)
~~~

FYI: The constant Whois::NAME was removed at b5466c5161fad79e295205e747dbe05c34336e7f