Move TFS URL match to user settings

This may be a clunky way of applying this feature - to be honest I have never messed with Chrome Extensions before. 

I had to change the permission scope to include all hosts, since to dynamically declare the TFS page, we can't inject based on match in the ```manifest.json``` file. So, my solution is to listen onActivated tab, and check the URL for one that matches the configuration setting, then essentially control the contextMenu. 

I'm (obviously) open to suggestions on how to accomplish this feature request if this doesn't turn out to be a good candidate.