NodeState is shared among nodes in the cluster (via gossip
in a gossip implementation) and cached locally in Cluster.Nodes
in order to be available to the /status endpoint.
Previously the cache type (`lru` or `ranked`) was determined by
checking the ending suffix of the frame. If it ended with a `.n`
then it was ranked. Otherwise it was an LRU.
This commit changes frames so that a `cacheType` option can be
passed in during creation to set either `lru` or `ranked`.
