Preparation of deployment for neon.ruby-lang.org

Just finished to preparation of deployment for neon.ruby-lang.org.

I created ```rubylang``` user and added vit-core team(@JEG2 @chikamichi @postmodern @stomar)'s public keys into authorized_keys. You can deploy after merge info master branch.

deployment is too easy capistrano task:

```shell
$ git clone git@github.com:ruby/www.ruby-lang.org.git
$ cd www.ruby-lang.org
$ cap deploy
```

Please check it.