Added 'tzinfo-data' if we are using jruby

I develop Rails on Windows, yepp...shame on me. With JRuby I find myself to add 'tzinfo-data' gem everytime I start a new project.
`RUBY_PLATFORM` with JRuby is always 'java', so we have to match this case, but It's a little bit 
tricky to find out if we are using JRuby on Windows.
I don't want to add and if-else clause for just one case, It's a problem to add it everytime we have Platform == 'java'? Can we add it to default if platform is jruby?
Otherwise we can check if:

```
Gem.win_platform? && PLATFORM.match(/java/)
```