Add support for "shared" experiments to the web pages. The begin
experiment form sports a new checkbox. When shared, the experiment information page will include a link (Shared) to a page where you can add and subtract projects that can share the nodes in the experiment. Only TBadmins and experiment creator and project leader get to mess with this stuff. A backed script called webnodeupdate is called to fire off updates on the nodes (accounts and mounts).