Include a helper to find right /dev/input

[albfan]

This oneliner can be used:

$  echo "/dev/grep -E  'Handlers|EV=' /proc/bus/input/devices |  grep -B1 'EV=120013' |  grep -Eo 'event[0-9]+'"
/dev/input/event4

Seems /dev/input/event4 is a common result

is based on http://stackoverflow.com/a/22568258