builder/openstack: address vet reports

Fixes the following vet reports:

builder/openstack/artifact.go:44: arg a.ImageId for printf verb %d of wrong type: string
builder/openstack/step_wait_for_rackconnect.go:24: arg server for printf verb %s of wrong type: *github.com/mitchellh/gophercloud-fork-40444fb.Server

builder/openstack/artifact.go

@@ -41,6 +41,6 @@ func (a *Artifact) State(name string) interface{} {
 }
 
 func (a *Artifact) Destroy() error {
-	log.Printf("Destroying image: %d", a.ImageId)
+	log.Printf("Destroying image: %s", a.ImageId)
 	return a.Conn.DeleteImageById(a.ImageId)
 }

builder/openstack/step_wait_for_rackconnect.go

@@ -21,7 +21,6 @@ func (s *StepWaitForRackConnect) Run(state multistep.StateBag) multistep.StepAct
 	csp := state.Get("csp").(gophercloud.CloudServersProvider)
 	server := state.Get("server").(*gophercloud.Server)
 	ui := state.Get("ui").(packer.Ui)
-	fmt.Printf("%s", server)
 
 	ui.Say(fmt.Sprintf("Waiting for server (%s) to become RackConnect ready...", server.Id))