DESIGN: Update flow_mod section to describe OpenFlow 1.1+ behavior.

Signed-off-by: Ben Pfaff <blp@nicira.com>
ofp-util: Add 'modify_cookie' to struct ofputil_flow_mod, to support OF1.1.

Signed-off-by: Ben Pfaff <blp@nicira.com>
tests: Add tests for mod flows with cookie miss on OF1.2.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Add basic OpenFlow 1.1 protocol support.

Signed-off-by: Ben Pfaff <blp@nicira.com>