Currently, oxm_ids argument of OFPActionCopyField should be a list of
OFPOxmId instances, but this patch enables to specify with the OXM field
name as the str type value which is corresponding to the keywords of
OFPMatch.
Signed-off-by: IWASE Yusuke <iwase.yusuke0@gmail.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>