do not fail open when in proximity

The default for blueproximity is that the unlocking command is specified as:
 - 'gnome-screensaver-command -d'

This is bad because it means there is an incentive to acquire someone's mobile phone (by hook or by crook) in order to access their machine.

Locking the screen has a failure mode of causing incoveinence to the user who may be at the keyboard but whose mobile phone is off / run out of battery - there is no problem.

But unlocking the screen can lead to all sorts of danger. There are likely users who want to do this -- it just should not be the default configuration. Perhaps ship a second configuration called 'permissive' preconfigured for those who wish unlocking to occur when they are in range.

Thanks,
Anand