Support for additional cluster.properties config

[vidkun]

It'd be nice to be able to specify additional cluster config settings for the cluster.properties file. Such as:

• ehcache.listener.hostName
• ehcache.listener.port
• ehcache.object.port

Right now, manually adding them causes them to be overwritten on next puppet run by the template.

Current work around is to perform initial provisioning of a Data Center node with datacenter => true, then set it to false and manually add additional config settings.