of12/3: support setting the oxm_value to OFPVID_NONE

In openflow spec 1.2 and 1.3.4, in order to match only packets without a VLAN tag,
the value of OFPXMT_OFB_VLAN_VID must be set to OFPVID_NONE (0x0000).
Old API of ofproto_v1_2/3_parser is now enabled to setting the oxm_value to OFPVID_NONE(0x0000) as follows:

e.g.)
    match = ofproto_v1_2_parser.OFPMatch()
    match.set_vlan_vid_none()

Signed-off-by: Minoru TAKAHASHI <takahashi.minoru7@gmail.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
test: add unittests for of1.3 parser

Signed-off-by: Minoru TAKAHASHI <takahashi.minoru7@gmail.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>