You could use something like this http://www.elecdirect.com/spst-normally-on-5aat12vdc-with-faceplate-1-screw-plunger-7-16-long?gclid=CJDJoJ2ZhMsCFUEfhgodo0cLOw
attached to the contacts on a monoprice or zwave sensor that has them. See this picture example
If you used two in series with the 1 monoprice you would get a notificiation any either door was open. just make a tab at the top middle of bottom middle of the doors to install them into.