Ensure metrics are also stored in Cassandra

[seanshahkarami]

It would be nice to have this data warehoused in Cassandra instead of just Elasticsearch in case Elasticsearch fails or we ever anticipate moving to another tool.

[seanshahkarami]

There's a process now which is storing all of this until we decide on how to approach the data pipeline.

For reference, the table layout is simple: ((node_id, date), timestamp, json metric data) This makes it trivial to start working with the data or moving it into the analytics pipeline.