bios: add support for custom bios
bios: add support for custom bios

Add Bios field into qemu Config struct, this allows to
start VM with custom bios

Partially fixes https://github.com/clearcontainers/runtime/issues/686

Signed-off-by: Julio Montes <4a43a13347431ef00be7d745d08a5ba1757e840b@intel.com>

ciao-project/ciao,kaccardi/ciao,rbradford/ciao,tpepper/ciao,tpepper/ciao,ciao-project/ciao,tpepper/ciao,rbradford/ciao,kaccardi/ciao,01org/ciao,01org/ciao