Go offline command for Team Foundation Server and Visual Studio 2015.
Version for VS 2013 is also avaliable here.
Version for VS 2012 is also avaliable here.
Version for VS 2017 is also avaliable on marketplace.
You can find new menu item in TEAM menu as "Go Offline", also in context menu of Solution Explorer. When executed, it switches current solution and all projects to Offline mode and you can work without acces to your Team Foundation Server.
Tested on TFS2013.
Based on GoOffline extension with permission of It's author Bernhard Tschirren.