Fix: Displays 'on host [object Object]' in log

Given provisioned **pm2-deploy** with multiple hosts like 

```js
  deploy : {
    production : {
      user : "ubuntu",
      host: [
          {
            host : "121.201.7.226",
            port: "58020"
          },
          {
            host : "192.168.33.80",
            port: "22"
          }
      ],
  ...
```

When deploy to remote, the log cannot show correct host deploying instead of `[object Object]`
```bash
$ pm2 deploy production setup
--> Deploying to production environment
--> on host [object Object]
  ○ running setup
  ○ cloning git@github.com:theone-dev/orange.git
```