Adapt the printed remaining time granularity when it is very high

We have a data importer and for big files, the remaining time reaches a high amount of seconds (>100'000). That makes the timing tough to estimate.

When the timing reaches say more than 5 minutes, would it be possible to display the time in minutes ? Same for minutes to hours and hours to days ?

reference: https://github.com/mcollina/seneca-import-csv/issues/1
