[Developers] deprecating /community/discussion_thread/updated

[Alec Flett]

Hey folks -
This change is a slight tweak to the discussion data model. If you're 
not writing an app that queries /community/discussion_thread, then you 
can ignore this.

In the next week or two, the discuss pages on www.freebase.com will stop 
updating the /community/discussion_thread/updated when someone posts, 
and we will probably garden out all the values from the graph.

This property is just residual cruft from an earlier data model. The 
proper thing to do now is to sort all posts in a discussion thread, and 
pick the 'updated' property for the most recent post.  With mql you can 
do this like this:

If you queries looked like this before:

{"id": "..."
 "type": "/community/discussion_thread",
 "updated": null }

And the updated time was in result["updated"]

Now it looks like this:

{"id": "..."
 "type": "/community/discussion_thread",
 "post": {"updated": null,
           "sort": "-updated", "limit": 1}}

And the the result["post"]["updated"] will have the equivalent semantic 
meaning.

Alec