Review 1013 (http://reviews.reviewboard.org/r/1013/) is useful to me, but I am trying to get a list of all of [latest] filenames in a review request.
This change extends Mak's (1013) change to allow me to do that.

This solution requires two JSON calls for me to get a list of filenames.
1) http://server/reviewrequests/%d/diff/
2) http://server/diff/%d/filenames/

In all honesty, I don't actually like needing to make two JSON calls when I could implement what I need in one JSON call.

So, Option #2, I would much prefer the a single request such as:
http://server/reviewrequests/%d/filenames/
(This always gets the filenames from the latest diff revision)

Option #3, another alternative, would be to get a list of filenames directly from a reviewrequest's diff revisions:
http://server/reviewrequests/%d/diff/latest/filenames/ 
http://server/reviewrequests/%d/diff/%d/filenames/ 


Option #3 is kindof slick, but I prefer Option #2, since this doesn't obligate me to complicate the API with a "latest" revision alias.



Finally, would Mak be OK w/ me changing his API from "/diff/" to "/diffs/"?

Change is still open to debate, so no test(s) added yet.