Add time ago tooltips to show actual date/time
Created by: dblessing
This implements the feature as requested in http://feedback.gitlab.com/forums/176466-general/suggestions/4910071-gitlab-should-show-yesterday-and-actual-dates-in
Each tooltip was visually inspected to make sure it looked good in its context. Most tooltips appear above the text. In a few cases it looked better to put the tooltip below the text.
Examples where the tooltip appears below the text: Project last activity - to avoid covering the project name
Comments - the top tooltip would appear behind the previous comment
Merge requests - to avoid covering merge request details "BRANCH > BRANCH" or "MERGED"
Please let me know if you would like additional screenshots.