Output directory is created if it doesn't exists. 

Pull Request for #574 .

Changes are on 'output-directory' branch.

:)
Remove this and use this directly:

```js
mkdirp(path.dirname(options.dest), function(err) {
  if (err) {
    return emitter.emit('error', chalk.red(err));
  }

  fs.writeFile(options.dest, result.css, function(err) {
    if (err) {
      return emitter.emit('error', chalk.red(err));
    }

    emitter.emit('warn', chalk.green('Wrote CSS to ' + options.dest));
    emitter.emit('write', err, options.dest, result.css);
    done();
  });
});
```