Offline version reporting improvements

This is a follow-up to #222 (closed).

The offline Version reporting feature could be a little improved. That can be addressed in this ticket.

• Customize feedback based on how long ago the data was manufactured (release date); e.g., don't show the green status "You are using the latest version" after 1 month from the release (only for BIND 9? or Kea and Stork too?).
• Tweak severity levels.
• Tweak feedback messages' wording.
• Raise the Version alert level to a red-colored error badge when Kea daemons mismatch was detected.
• Update help tooltip content according to ARM updates done in #1566 (closed).
• There was the idea to inform about EoL'ed Version used - but we lack the data to determine whether a current old version is EoL'ed. We only display EoL date for current releases.
• Do not show Dev release in Kea/Bind9/Stork tables if latest Dev < latest Stable.
• Accept release metadata without Development release (stable release only).
• Accept array of security releases (for all stable branches) instead of one security release.