Client-side validation for NaN field values

[dmjef]

When you submit a metric with a NaN value of a field, it fails server-side with "org.influxdb.InfluxDBException: http: bad request". It would be nice to have client-side validation with a better error message as it can be a bit annoying to track down the cause of the "bad request".

[asashour]

I guess if it is implemented in InfluxDB, we wouldn't need this.

Please look into influxdata/influxdb#4089