test_dhcp: Extend unit test for fragmented options
test_dhcp: Extend unit test for fragmented options

Also, this patch removes the test case for __init__()
with "hlen" is zero,
because "hlen" should be recalculated at serialization.

Signed-off-by: Shinpei Muraoka <154d36ff5308ea67e46435bebcfb51dcc823bd4d@gmail.com>
Signed-off-by: FUJITA Tomonori <93dac1fe9c4b2a3957982200319981492ad4976e@lab.ntt.co.jp>

fujita/ryu,lagopus/ryu-lagopus-ext,iwaseyusuke/ryu,shinpeimuraoka/ryu,pichuang/ryu,osrg/ryu,lagopus/ryu-lagopus-ext,fujita/ryu,pichuang/ryu,pichuang/ryu,gareging/SDN_Framework,fujita/ryu,gareging/SDN_Framework,shinpeimuraoka/ryu,pichuang/ryu,pichuang/ryu,iwaseyusuke/ryu,gareging/SDN_Framework,lagopus/ryu-lagopus-ext,fujita/ryu,osrg/ryu,shinpeimuraoka/ryu,osrg/ryu,iwaseyusuke/ryu,fujita/ryu,lagopus/ryu-lagopus-ext,iwaseyusuke/ryu,gareging/SDN_Framework,gareging/SDN_Framework,iwaseyusuke/ryu,shinpeimuraoka/ryu,osrg/ryu,shinpeimuraoka/ryu,osrg/ryu,lagopus/ryu-lagopus-ext