pyang_plugins: pep8 style fix

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
tox.ini: Add pep8 environment

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
test_parser: Make this independent from test environment path

To make this able to run via testr.

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
test_addrconv: Fix a way to import the tested module

I'm not quite sure how it happens to work with the current
test environment.  But the current coding doesn't work when
running via testr probably due to different PYTHONPATH.

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

Also, run pep8 in a separate environment.

The way to specify python versions might seem awkward.
(Well, it seems so to me.)
But it follows one of examples referenced in the official
documentation:
    http://docs.travis-ci.com/user/languages/python/
    https://github.com/twisted/klein/blob/master/.travis.yml

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

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

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
oxm_fields: Add Nicira Extended Match (NXM) support

Note: It wasn't clear to me which NXM stands for "Extensible" or
"Extended".  I chose the latter because it's in the primary
specification.  (nicira-ext.h)

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
ofproto_v1_3: Add tun_ipv4_src and tun_ipv4_dst NXMs

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
packet_data_generator: Add tun_ipv4_src and tun_ipv4_dst for OF1.3

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

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

Update after tun_ipv4_src/tun_ipv4_dst changes.

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