not hardcode Operation when creating arp pkt

Signed-off-by: Vasiliy Tolstov <v.tolstov@selfip.ru>
int -> uint16

Signed-off-by: Vasiliy Tolstov <v.tolstov@selfip.ru>
try to parse icmp and udp

Signed-off-by: Vasiliy Tolstov <v.tolstov@selfip.ru>
Merge pull request #6 from vase/ipv4

try to parse icmp and udp
Merge pull request #5 from vase/arp

when create arp packet provide operation
i forget
Merge branch 'master' of github.com:jonstout/pacit