How do I enable a user to sudo without password?

I have a php script with this:

<?php
#echo exec('whoami');

$output = shell_exec('bash /usr/local/svn/bash_repo/make-live');
echo "$output";
?>

The make-live script contains this:

#!/bin/bash

cd /var/www-cake

sudo svn checkout file:///usr/local/svn/bash_repo/repo/

echo "Head revision has been pushed to live server"

So the PHP user who is www-data needs to have nopasswd for that script. I am told I need to add:

www-data ALL=NOPASSWD: /usr/local/svn/bash_repo/make-live

To sudoers to allow this. First I run sudo visudo but I have no experience with vi so I try to open it in gedit with export EDITOR=gedit && sudo -E visudo which then just opens a sudoers.tmp file which is empty. I add the line and save it. But it doesn't do save.

So I just try sudo visudo and I add the line right beneath this part:

# User privilege specification
root    ALL=(ALL) ALL
www-data ALL=NOPASSWD: /usr/local/svn/bash_repo/make-live

I closed out sudoers and reopened to verify that it has saved. I even restart apache.

I run the php file and it still doesn't work.

What am I missing?