Show emergency numbers in flight mode

This solves

https://bugs.launchpad.net/ubuntu/+source/ofono/+bug/1366186

and

https://bugs.launchpad.net/ubuntu/+source/ofono/+bug/1366188
I know we don't explicitly check for these new atoms against NULL anywhere in the code, but it still would probably be safer to explicity set them to NULL after removing them.