Fix redis-yml instructions

[hibariya]

I noticed node['utility_instances'] doesn't have hostname. This is a fix for that.

[radamanthus]

I tried it out and I encountered the error:

NameError
---------
no member 'hostname' in struct

Cookbook Trace:
---------------
  /etc/chef-custom/recipes/cookbooks/redis-yml/recipes/default.rb:20:in `[]'
  /etc/chef-custom/recipes/cookbooks/redis-yml/recipes/default.rb:20:in `block (2 levels) in from_file'
  /etc/chef-custom/recipes/cookbooks/redis-yml/recipes/default.rb:12:in `block in from_file'
  /etc/chef-custom/recipes/cookbooks/redis-yml/recipes/default.rb:11:in `from_file'
  /etc/chef-custom/recipes/cookbooks/main/recipes/default.rb:1:in `from_file'

Relevant File Content:
----------------------
/etc/chef-custom/recipes/cookbooks/redis-yml/recipes/default.rb:

 13:          source 'redis.yml.erb'
 14:          owner node[:owner_name]
 15:          group node[:owner_name]
 16:          mode 0655
 17:          backup 0
 18:          variables({
 19:            :environment => node[:environment][:framework_env],
 20>>           :hostname => redis_instance[:hostname]
 21:          })
 22:        end
 23:      end
 24:    end
 25:  end
 26:

I had to change line 5 from:

redis_instance = node.engineyard.environment.instances.find { |instance| instance[:role] == 'util' }

to:

redis_instance = node[:engineyard][:environment][:instances].find { |instance| instance[:role] == 'util' }

and

line 20 to

hostname => redis_instance[:public_hostname]