openruko keys:add fails, when following the README

If you follow the README carefully, you cannot deploy. The user openruko@openruko.com is not created by default, and README dont inform this. Looks like you need to manually create an user after `vagrant up`. This pull-request fixes the README. 

In fact, after you create the user you still stuck at `openruko key:add`:

```
vagrant@precise64:~/myapp$ ~/openruko/client/openruko keys:add
Enter your Heroku credentials.
Email: openruko@openruko.com
Password (typing will be hidden):
Found existing public key: /home/vagrant/.ssh/id_rsa.pub
Uploading SSH public key /home/vagrant/.ssh/id_rsa.pub... failed
 !    Heroku client internal error.
 !    Search for help at: https://help.heroku.com
 !    Or report a bug at: https://github.com/heroku/heroku/issues/new

    Error:       read timeout reached (Excon::Errors::Timeout)
    Backtrace:   /usr/local/heroku/vendor/gems/excon-0.22.1/lib/excon/socket.rb:80:in `rescue in read'
                 /usr/local/heroku/vendor/gems/excon-0.22.1/lib/excon/socket.rb:75:in `read'
                 /usr/local/heroku/vendor/gems/excon-0.22.1/lib/excon/ssl_socket.rb:72:in `read'
                 /usr/local/heroku/vendor/gems/excon-0.22.1/lib/excon/response.rb:36:in `parse'
                 /usr/local/heroku/vendor/gems/excon-0.22.1/lib/excon/connection.rb:352:in `response'
                 /usr/local/heroku/vendor/gems/excon-0.22.1/lib/excon/connection.rb:249:in `request'
                 /usr/local/heroku/vendor/gems/heroku-api-0.3.11/lib/heroku/api.rb:76:in `request'
                 /usr/local/heroku/lib/heroku/auth.rb:20:in `request'
                 /usr/local/heroku/vendor/gems/heroku-api-0.3.11/lib/heroku/api/keys.rb:37:in `post_key'
                 /usr/local/heroku/lib/heroku/auth.rb:290:in `block in associate_key'
                 /usr/local/heroku/lib/heroku/helpers.rb:236:in `action'
                 /usr/local/heroku/lib/heroku/auth.rb:288:in `associate_key'
                 /usr/local/heroku/lib/heroku/auth.rb:257:in `associate_or_generate_ssh_key'
                 /usr/local/heroku/lib/heroku/command/keys.rb:67:in `add'
                 /usr/local/heroku/lib/heroku/command.rb:206:in `run'
                 /usr/local/heroku/lib/heroku/cli.rb:28:in `start'
                 /usr/bin/heroku:25:in `<main>'

    Command:     heroku keys:add
    Host:        mymachine.me:5000
    Version:     heroku-toolbelt/2.39.5 (i686-linux) ruby/1.9.3
```

Is there something wrong with what I had done following the README?