fix(whois): check if there's at least one argument to whois

This avoids thefuck failing when there's no arguments. It fails with:

```
  ...
  File "thefuck/rules/whois.py", line 26, in get_new_command
    url = command.script.split()[1]
IndexError: list index out of range
```

Signed-off-by: Pablo Santiago Blum de Aguiar <scorphus@gmail.com>

thefuck/rules/whois.py

@@ -19,7 +19,7 @@ def match(command, settings):
         - www.google.fr → subdomain: www, domain: 'google.fr';
         - google.co.uk → subdomain: None, domain; 'google.co.uk'.
     """
-    return 'whois' in command.script
+    return 'whois' in command.script and len(command.script.split()) > 1
 
 
 def get_new_command(command, settings):