BT40 device discovery fixups

A few fixups for BT40 discovery, we now search for BT40
devices properly.

- delete BT40 properly
- scan for longer
- return count of total found
- a few fixups to logic in AddDeviceWizard

Now need to update the pair screen to let the user
select/deselect sensors that are part of this "device".

Then obviously update the BT40/Controller for runtime
activity (and filter out the RFLKT since it will have
its own device type.