Record how long each HIT took to complete. Lists results on status_details page.
Will list the duration time to do the HIT and the time it was submitted.
Duration time is calculated by page load time and "unload" time.
Only works on HITs done within the same browser.
Refreshing the page will reset the load time.
Database will purge entries older than 151 days. (status_details can go back 150 days.)
This script is in a testing phase.
v3.0.20180210 - Automatically convert older database to deal with status_details lag.
