Ohai 7 handles plugins a bit differently

Opted to handle Ohai 6 and 7 to be safe.

    [2014-05-01T05:05:55+00:00] ERROR: ohai[reload_passwd] (nsq::accounts line 30) had an error: Ohai::Exceptions::AttributeNotFound: No such attribute: 'passwd'
Merge pull request #3 from retr0h/retr0h/correct-ohai-account-plugin

Ohai 7 handles plugins a bit differently