words' regex argument crashes with quantifiers

As soon as I add a quantifier in `words`' pattern argument, I get an error I wouldn't with the original JS method split:

``` javascript
var a = _('1 2, 3').words(/, +/);
// => SyntaxError: Invalid regular expression: /^, ++|, ++$/: Nothing to repeat
var b = _('1 2, 3').words(/, */);
// => SyntaxError: Invalid regular expression: /^, *+|, *+$/: Nothing to repeat
var c = _.words('1 2, 3', /, */)
// => SyntaxError: Invalid regular expression: /^, *+|, *+$/: Nothing to repeat
```

See this jsfiddle: http://jsfiddle.net/ejoubaud/J9gn9/

Unrelated: Why use the obscure name `words` instead of the basic JS/Ruby well-known `split` ? I'd strongly +1 an alias.

Apart from that awesome job with this lib guys, thank you very much.