Display time since last release

[phil9909]

Summary

Show the last release time (or "never released") when hovering over release details.
It uses the moment library to display human readable time deltas (e.g. "2 months ago", "3 days ago")

Notice: In the screenshots you can't see my cursor, as Ubuntu seems to "helpfully" hide them from the Screenshot.

Use Cases

Fixes #9

Checklist

• I have viewed, signed, and submitted the Contributor License Agreement.
• I have linked issue(s) that this PR should close using keywords or the Github UI (See docs)
• I have added an integration test, if necessary.
• I have reviewed the styleguide for guidance on my code quality.
• I'm happy with the commit history on this PR (I have rebased/squashed as needed).