Yeah, Ridley sets up it's own pool, rather than using the Celluloid init codepath, and for some reason that doesn't get initialized when I use it here.  The Celluloid setup in Ridley was doing my head in though...

Here's the backtrace:
```
/opt/sensu/embedded/lib/ruby/gems/2.0.0/gems/celluloid-0.15.2/lib/celluloid/internal_pool.rb:28:in `assert_running': Thread pool is not running (Celluloid::Error)
        from /opt/sensu/embedded/lib/ruby/gems/2.0.0/gems/celluloid-0.15.2/lib/celluloid/internal_pool.rb:64:in `block in get'
        from /opt/sensu/embedded/lib/ruby/gems/2.0.0/gems/celluloid-0.15.2/lib/celluloid/internal_pool.rb:63:in `synchronize'
        from /opt/sensu/embedded/lib/ruby/gems/2.0.0/gems/celluloid-0.15.2/lib/celluloid/internal_pool.rb:63:in `get'
        from /opt/sensu/embedded/lib/ruby/gems/2.0.0/gems/celluloid-0.15.2/lib/celluloid/thread_handle.rb:10:in `initialize'
        from /opt/sensu/embedded/lib/ruby/gems/2.0.0/gems/celluloid-0.15.2/lib/celluloid/actor.rb:155:in `new'
        from /opt/sensu/embedded/lib/ruby/gems/2.0.0/gems/celluloid-0.15.2/lib/celluloid/actor.rb:155:in `initialize'
        from /opt/sensu/embedded/lib/ruby/gems/2.0.0/gems/celluloid-0.15.2/lib/celluloid.rb:188:in `new'
        from /opt/sensu/embedded/lib/ruby/gems/2.0.0/gems/celluloid-0.15.2/lib/celluloid.rb:188:in `new'
        from /opt/sensu/embedded/lib/ruby/gems/2.0.0/gems/ridley-1.7.1/lib/ridley/client.rb:34:in `open'
        from /opt/sensu/embedded/lib/ruby/gems/2.0.0/gems/ridley-1.7.1/lib/ridley.rb:51:in `open'
        from /etc/sensu/handlers/other/chef_node.rb:51:in `chef_node_exists?'
        from /etc/sensu/handlers/other/chef_node.rb:80:in `handle'
        from /opt/sensu/embedded/lib/ruby/gems/2.0.0/gems/sensu-plugin-0.1.7/lib/sensu-handler.rb:41:in `block in <class:Handler>'
```