make header's Serialize() use its' Version and Marker
make header's Serialize() use its' Version and Marker

Preparation for multi version support.

Signed-off-by: FUJITA Tomonori <93dac1fe9c4b2a3957982200319981492ad4976e@lab.ntt.co.jp>

osrg/gozebra,postfix/gozebra,codeout/gozebra