I had to revise the cookbook in the following ways:
 - We need to be able to set the ['redisio']['servers'] attribute in default_attributes.  Otherwise we cannot manually edit node files to point slaves to masters.
 - We cannot set that attribute in default_attributes without getting rid of the cookbook's default attribute for servers, so I did that.
 - I also got rid of the default save setting, so we could set it in ['redisio']['default_settings'] without having to deal with these annoying merge attribute issues.  This will allow us to have our slave roles use the masters in their run lists.