Including total or average queued duration for a Connection within ConnectionStatus

[Kessler, Jon]

When listing the contents of a connection you can see the queued duration for 
individual FlowFiles. I believe that could also be a valuable metric to include 
in the ConnectionStatus that is accessible by reporting tasks as it pertains to 
the entire connection to give you a sense of how long files are waiting to be 
processed on average. I intend to open a ticket for this feature but wanted to 
solicit discussion on it as well.