Bug 1051172: a willhide event hack so the camera can stop recording quicker when home button pressed

For app launches, when we're at the homescreen, the callback function will be called synchronously.

When apps are closing, I purposely want to send the signal via the settings db before we start switching the app. Becasue the moment we touch activate the new app or homescreen, we're going to start swapping and slowing things down.