packet lib: igmp: support default parameters

Signed-off-by: Yuichi Ito <ito.yuichi0@gmail.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
add OpenFlow 1.4 definitions

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Merge branch 'master' of github.com:osrg/ryu into working
Merge pull request #2 from changbl/working

Syn with Ryu 9305ef9b7b27c09db5cec4dda362e0c3ff8a3280