bugfix (Moji.zen_to_han(" ") returns "0...3") in Ruby >= 1.9

in Ruby 1.9.3, Moji.zen_to_han returns weird output:

```ruby
Moji.zen_to_han(" ") #=> "0...3"
```

This bug does not affect 1.8.7. Here's a quick fix for it (Tested on 1.8.7 and 1.9.3).

I hope it helps.