v-sim

and scanner selector example ``` $ scanimage -L device `hpaio:/net/hp_laserjet_cm1415fn?ip=192.168.1.100&queue=false' is a Hewlett-Packard hp_laserjet_cm1415fn all-in-one device `hpaio:/net/officejet_pro_7740_series?ip=192.168.1.102&queue=false' is a Hewlett-Packard officejet_pro_7740_series all-in-on e ```