ubuntu@localhost:~$ sudo ./snappy install oem-hardware-assign_1.0_all.snap --allow-unauthenticated
Installing oem-hardware-assign_1.0_all.snap
2015/04/20 10:52:43 Signature check failed, but installing anyway as requested
Name                Date       Version Developer 
ubuntu-core         2015-04-20 404     ubuntu    
oem-hardware-assign 2015-04-20 1.0     sideload  
ubuntu@localhost:~$ sudo udevadm info /dev/ttyS0 
P: /devices/pnp0/00:05/tty/ttyS0
N: ttyS0
E: DEVNAME=/dev/ttyS0
E: DEVPATH=/devices/pnp0/00:05/tty/ttyS0
E: MAJOR=4
E: MINOR=64
E: SUBSYSTEM=tty
E: TAGS=:systemd:
E: USEC_INITIALIZED=51308

ubuntu@localhost:~$ sudo udevadm trigger --tag-match=snappy-assign -vubuntu@localhost:~$ sudo udevadm control --reload
ubuntu@localhost:~$ sudo udevadm control --reload -v
control: invalid option -- 'v'
ubuntu@localhost:~$ sudo udevadm control --reload 
ubuntu@localhost:~$ sudo udevadm trigger --tag-match=snappy-assign -v
ubuntu@localhost:~$ sudo udevadm info /dev/ttyS0 P: /devices/pnp0/00:05/tty/ttyS0
N: ttyS0
E: DEVNAME=/dev/ttyS0
E: DEVPATH=/devices/pnp0/00:05/tty/ttyS0
E: MAJOR=4
E: MINOR=64
E: SUBSYSTEM=tty
E: TAGS=:systemd:
E: USEC_INITIALIZED=51308

ubuntu@localhost:~$ cat /etc/udev/rules.d/80-snappy_oem-hardware-assign_oem-hardware-assign.sideloaded.rules 
KERNEL=="ttyS0", TAG:="snappy-assign", ENV{SNAPPY_APP}:="oem-hardware-assign.sideloaded"

KERNEL=="ttyUSB0", TAG:="snappy-assign", ENV{SNAPPY_APP}:="oem-hardware-assign.sideloaded"