plugin's gemfile also needs tzinfo-data in Windows

```
rails plugin new foo
cd foo
rake test
```

Fails in Windows, due to the dependency on `tzinfo-data` gem. Just like 9d664b18df7a81b75e45bb99858f920de040e9fb, c8ccab05277dd5639cea509c2911af6ee35b0cf9, bf993fac57bb1cb69ec46d2bbc2f2752bcd844ae, automatic bundle doesn't hurt, I think.