Use strings in preference to symbols to access node attributes

[willejs]

As per foodcritic FC001 rule, strings should be used instead of symbols.
someone run something like this, but better
echo "node[:etcd][:upstart][:start_on]" | sed "s/]/']/g" | sed "s/:/'/g"

[spheromak]

@willejs this is just a bike shed style rule I prefer symbols, but if enough people care I am happy to switch it.

[willejs]

Its the never ending argument...
Foodcritic/foodcritic#86