of1.3: Add special group identifier values defined on OpenFlow 1.3.1

This patch add missing group special values of OpenFlow 1.3, added to
the 1.3.1 version.

It is useful to create a flow_mod message with an out_group with no >
group restrictions and for flow_stats messages.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
doc: fix the mailing list address

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
ofproto/nx_match: pep8

> $ pep8 --version
> 1.4.5
> ryu/ofproto/nx_match.py:743:20: E128 continuation line under-indented for visual indent
>                    ofproto_v1_0.NXM_NX_IPV6_SRC_W])
>                    ^
> ryu/ofproto/nx_match.py:764:20: E128 continuation line under-indented for visual indent
>                    ofproto_v1_0.NXM_NX_IPV6_DST_W])
>                    ^

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
lib/packet/arp.py: add convenience function to create arp for ip

Since ip case is most often used, introduce a convenience
function for that.

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
ofproto/inet: add VRRP protocol number

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
lib/packet/ipv4: add constants for parse/serialize

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
lib/packet/ipv6: add constants for parse/serialize

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
lib/packet: VRRP packet parser/serializer

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
tests/unit, lib/packet/vrrp: unit test for vrrp packet parser/serializer

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
packet lib: docstring

also, prefix a private method with _.

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
g/c a stale reference to find_protocol

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>