Incorrect Usage with -mode=flat

[clinta]

Steps to reproduce:

1. Build from Dockerfile:

$ docker build -t ovs-plugin .

1. Run in flat mode:

$ docker run -v /run/docker/plugins:/run/docker/plugins -v /var/run/docker.sock:/varun/docker.sock --net=host --privileged ovs-plugin --gateway=192.168.1.1 --bridge-subnet=192.168.1.0/24 -mode=flat
Incorrect Usage.

NAME:
   don - Docker Open vSwitch Networking

USAGE:
   don [global options] command [command options] [arguments...]

VERSION:
   0.2

COMMANDS:
   help, h  Shows a list of commands or help for one command

GLOBAL OPTIONS:
   --debug, -d      enable debugging
   --help, -h       show help
   --version, -v    print the version