Build a Simple Collaboration Tool (Website)

I would like to build a simple online collaboration tool for short development projects (mostly for regression testing and sharing results). This would be a basic CMS with two user permissions levels. A standard user will be able to create a new thread that is locked behind an auto generated password. He can then copy the link and password to share with his team members to communicate in the thread. The admin level would be for moderation and just display all posts in a chronological order. There is a wires and function document attached that gives more details including a project summary, basic user flows and functional breakdown of each page and page-state. I require a quote on development of the backend (on Ruby on Rails) and the visual layers (HTML/CSS/Javascript) for this project. I haven't done designs as yet but the site is purposely bare-bones and very simple - the visual layers will not be complex. There is no requirement for the site to be responsive. The limited functionality is designed to make using it as easy as possible and as cheap as possible to create and release - the function is all based off simple Ruby projects I've done in the past and Gems I know exist.