fixed edge case for AMv3 POA geni_update_users
There was a weird edge case for AMv2 PerformOperationalAction geni_update_users.
undef was used as
$key, which was passed along from call to call all the way from
$keychecker sub. In that sub, the code
$key ne "" caused a crash.
This should now be fixed, by adding
if (defined($key)) to GeniAM.pm.in