How to change the file upload directory on version 3.5?

The option to change the upload folder for images is gone on version 3.5, any way to make it visible again or a workaround ?

From this core ticket:

Changing the upload_path and upload_url_path options are pretty dangerous. They have the potential to break quite a bit of things, not to mention they have the potential of simply not working.
[…]
There’s really no good reason to show upload_path or upload_url_path in the UI unless the values are other than the default (wp-content/uploads or ” for upload_path, and ” for upload_url_path). With that, most of a section disappears, leaving just year/month folder organization.

In addition to what Joseph suggested, you can also define the upload path in the wp-config.php file like this:

define( 'UPLOADS', 'wp-content/'.'files' );

If you’d like it outside the wp-content folder, specify path like this:

define( 'UPLOADS', ''.'uploads' );

For uploading to a folder like example.com/images, use this code:

//Custom upload path
define( 'UPLOADS', ''.'images' );