tools: allow multiple added: version entries

Allow multiple `added:` version entries, since semver-minors
can trickle down to previous major versions, and thus
features may have been added in multiple versions.

Also include `deprecated:` entries and apply the same logic
to them for consistency.

Stylize the added HTML as `Added in:` and `Deprecated since:`.

PR-URL: https://github.com/nodejs/node/pull/6495


Reviewed-By: Robert Jefe Lindstaedt <robert.lindstaedt@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>