"This tool is used to install and remove CASE Add-Ins from any version of Revit. We will no longer build ClickOnce installers for any of the free tools. You may also notice a little preview for our upcoming subscription tools... stay tuned to the www.case-inc.com site for announcements!!"
This free add-in may be downloaded from the Case Apps website.
Update 5/8/2016: CASE and the CASE Apps website are no more but, courtesy of WeWork, the CASE Apps are now open source. They may be accessed on GitHub.