provisioner/remote-exec: Clear out scripts after uploading

Prevents residual script contents from remaining on machine.

Fixes #483

builtin/provisioners/remote-exec/resource_provisioner.go

@@ -192,6 +192,13 @@ func (p *ResourceProvisioner) runScripts(
  return fmt.Errorf("Error starting script: %v", err)
  }
 
+ // Upload a blank follow up file in the same path to prevent residual
+ // script contents from remaining on remote machine
+ empty := bytes.NewReader([]byte(""))
+ if err := comm.Upload(remotePath, empty); err != nil {
+ return fmt.Errorf("Failed to upload empty follow up script: %v", err)
+ }
+
  return nil
  })
  if err == nil {