vlandev: Fix an obvious predicate logic crash bug.

Signed-off-by: ZhengLingyun <konghuarukhr@163.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>
SubmittingPatches: Rename to CONTRIBUTING.

This makes the GitHub interface aware of the contribution guidelines,
so it will be displayed to contributors when they submit issues or pull
requests.

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