Improve defense if InfluxDb goes down for FpcHitRate

[mpchadwick]

What happens if InfluxDb goes down

• In progress requests pile up and are never deleted
• If this isn't addressed, redis store could fill up which could create performance issues for the application as every request will try to write to the redis store.

Solutions

• Set an expiry when creating InProgress keys. We lose the data if InfluxDb goes down for an extended period of time, but we decrease possibility of jeopardizing application performance
• Also, check for InProgress keys during send. Use timestamp added to in progress flag when sending to InfluxDb