Adjust "Last Updated" status across project

Recently we made changes to the witnesses page so as we have a fontawesome icon showing for last updated. We need to make 2 additional changes:

• The delay is missing the word "ago", so it should say for example "5 mins ago" in both display and tooltip
• We need to implement the same approach everywhere "Last Updated" is used, for instance in the "Voters" and "Votes History" popups. If there are other areas let's update them as well for consistency