print usage information when no option is given
print usage information when no option is given

When no option is given pkcsconf does nothing and quits silently with a zero
return code. It should output the usage information and return non-zero code.

Signed-off-by: Dan Horák <2591e5f46f28d303f9dc027d475a5c60d8dea17a@danny.cz>

joylatten/opencryptoki,shpedoikal/opencryptoki,shpedoikal/opencryptoki,joylatten/opencryptoki,fingunter/OpenCryptoki,fingunter/OpenCryptoki,joylatten/opencryptoki,fingunter/OpenCryptoki,shpedoikal/opencryptoki,fingunter/OpenCryptoki,shpedoikal/opencryptoki,joylatten/opencryptoki,joylatten/opencryptoki