cleanup udp, more error checking

Signed-off-by: Vasiliy Tolstov <v.tolstov@selfip.ru>
add error checking

Signed-off-by: Vasiliy Tolstov <v.tolstov@selfip.ru>
Merge pull request #7 from vtolstov/cleanup

Cleanup for arp messages
merging
fix dhcp msg size

Signed-off-by: Vasiliy Tolstov <v.tolstov@selfip.ru>
Merge branch 'dhcp' of github.com:vtolstov/pacit into dhcp

Conflicts:
	dhcp.go