Migrate export command to cobra

Signed-off-by: Vincent Demeester <vincent@sbr.pm>

cobraadaptor/adaptor.go

@@ -34,6 +34,7 @@ func NewCobraAdaptor(clientFlags *cliflags.ClientFlags) CobraAdaptor {
 	rootCmd.SetOutput(stdout)
 	rootCmd.AddCommand(
 		container.NewCreateCommand(dockerCli),
+		container.NewExportCommand(dockerCli),
 		container.NewRunCommand(dockerCli),
 		image.NewSearchCommand(dockerCli),
 		volume.NewVolumeCommand(dockerCli),

usage.go

@@ -15,7 +15,6 @@ var DockerCommandUsage = []Command{
 	{"diff", "Inspect changes on a container's filesystem"},
 	{"events", "Get real time events from the server"},
 	{"exec", "Run a command in a running container"},
-	{"export", "Export a container's filesystem as a tar archive"},
 	{"history", "Show the history of an image"},
 	{"images", "List images"},
 	{"import", "Import the contents from a tarball to create a filesystem image"},