Fix firefox crash when command line adb is started.

This removes the exit(0) when adb tells us to close and instead triggers our close function.  Unfortunately, once closed the app manager connection doesn't currently work again until firefox is restarted.  Also, the device doesn't show up to adb until it is replugged.

Next I'm going to try to get it into a state where close() and start() can be called and everything will work again.