test_ofctl_v1_2/3: Fix some test cases

UnitTest of the following cases had not been executed successfully.

{'dl_src/dst': "aa:bb:cc:11:22:33/*"}
{'eth_src/dst': "aa:bb:cc:11:22:33/*"}
{'nw_src/dst': "192.168.0.1/*", 'eth_type': 0x0800}
{'ipv4_src/dst': "192.168.0.1/*", 'eth_type': 0x0800}
{'arp_spa/tpa': "192.168.0.22/*", 'eth_type': 0x0806}
{'arp_sha/tha': "aa:bb:cc:11:22:33/*", 'eth_type': 0x0806}
{'ipv6_src/dst': '2001::aaaa:bbbb:cccc:1111/*', 'eth_type': 0x86dd}

This patch fixes this problem.

Signed-off-by: Minoru TAKAHASHI <takahashi.minoru7@gmail.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
test_ofctl_v1_2/3: Add a test case of masked metadata

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

The parameter buf is an instance of bytearray, but Ryu tries to convert it as string,
and outputs the error messages as a result.
This patch fixes this problem.

Signed-off-by: IWASE Yusuke <iwase.yusuke0@gmail.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
test_utils: Add unit test for ryu.utils

Signed-off-by: IWASE Yusuke <iwase.yusuke0@gmail.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>