Improve witnesses display of feed age

Currently the witnesses page displays the feed age in a format not very human readable with a mix between hours/mins and or days ago (see screenshot below)

we would like to adjust this display so that it is unified displaying formats with the smallest unit being mins and the largest being days (3 mins, 5 mins, 1 hour, 2 hours, 1 day, 2 days, 50 days, 300 days)

Also if the age is older than 3 days we would like to highlight in red