agile: convert story into analysis story and move it t release notes

We have been doing a lot of analysis on Clean up meta-data tagger by
improving ptree API during build downtimes, etc. It makes sense to
convert this into a pure analysis story, ship it this iteration and
create a more "codable" story on the back of it with concrete changes
to the API. So:

- rename story to Design a cleaner meta-data API;
- move it to current sprint
om: check for integrated io before including iosfwd

We were blindly including iosfwd without checking to see if it was
needed. This was a regression but got rebaselined by mistake.