SAN FRANCISCO -- San Francisco has been tinkering with the idea of micro-apartments, but the latest venture may be going a bit too far.According to the real estate web page SocketSite , a developer wants to convert a used car lot on South Van Ness and 15th Street into a high-density apartment building. Each unit would be less than 200-square-feet.That's enough space for a microwave, a pull-down Murphy bed, and a sink that is built into the top of the toilet to save room.Residents would share a community kitchen and lounge. The developer calls it group housing for the sharing economy.