How to create a user that can not create new projects

Hi, I’m deploy KoboToolbox for one awesome project!

I use the Uploading users in bulk in Django - #8 by Josh solution by @Josh to upload a thousand users, but I need that some users can not access via front end and / or can not create new projects (this second is mandatory, they can not create new projects because they don’t need to do that).

I really appreciate your support.

Thanks!