rest_router: avoid assertion when ip_text is 0

Signed-off-by: Wataru ISHIDA <ishida.wataru@lab.ntt.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
rest_router: convert haddr to bin for OFPActionSetDlSrc/Dst

Signed-off-by: Wataru ISHIDA <ishida.wataru@lab.ntt.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>