ctools context plugin for user subdomain

Issue Summary

I use the enclosed ctools context plugins to use a user subdomain in context. For example, a view with a user argument can be hooked up in a mini-panel to the user subdomain context. This allows the view content to be tailored depending on what URL the site is accessed through, i.e. userx.domain.com, usery.domain.com. Just add the file to the ctools/plugins/contexts/ directory. If useful and appropriate I would be happy if you added this to your excellent project.