Admin Authors page should also indicate number of draft for each author [w/ patch]

[coffee2code]

The "Authors & Users" subpage under "Users" in the Admin section should also indicate the number of drafts each author has, especially since there is no real way of assessing who has how many drafts (the "Manage" page will of course list the titles of all drafts, and of course a click-through on each will reveal the authors, but summarizing the draft count on a per-author basis might be of value).