Initial OpenFlow 1.3 support

Initial OpenFlow 1.3 support

Initial OpenFlow 1.3 support with new include/openflow/openflow-1.3.h.
Most of the messages that differ from 1.2 are implemented. OFPT_SET_ASYNC
is implemented via NX_SET_ASYNC_CONFIG, other new message types are yet to
be implemented. Stats replies that add duration fields are implemented at
encode/decode level only. Test cases for implemented features are included.
Remaining FIXME:s should not cause runtime aborts. Make check comes out
clean.

Signed-off-by: Jarno Rajahalme <jarno.rajahalme@nsn.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>