add ark from repo to fix bug with Chef 11
Ruby 1.9.3-p392 is now required

There is a denial of service vulnerability in the JSON parser included with Ruby.

Denial of Service and Unsafe Object Creation Vulnerability in JSON (CVE-2013-0269)
http://www.ruby-lang.org/en/news/2013/02/22/json-dos-cve-2013-0269/

This vulnerability is fixed in the latest patch release of Ruby 1.9.3-p392:
http://www.ruby-lang.org/en/news/2013/02/22/ruby-1-9-3-p392-is-released/

I've updated the required Ruby used for lab from 1.9.3-p385 to 1.9.3-p392.
bump data_bags, added Piotr's public key
add Piotr to deploy user authorized_keys