Run smoke test again Java Early Access Release

Run smoke test again JDK9 and JDK8 with `jjs` or `java`.

```
rake jdk8_ea
rake jdk9_ea
```

Currently JDK9 is not working.
Here's the code used in RubyGems itself.

https://github.com/rubygems/rubygems/blob/master/lib/rubygems/package.rb#L320-L376