App to shut down/restart phone?

[DallasXanadu]

After a coffee mishap, my lock button is not functioning (and finding a place to repair it in Dallas has proven most difficult). I've got an app to lock screen, and I use double tap to unlock, but am looking for an app to force shut down/reboot. I see a few in the app store, but reviews state they don't work on 8.1. Who's got one for me?