Requests for comment/image and oldimage tables

There's no auto-incrementing primary key for, and no primary key at all for. This should be changed so we can add an imgids parameter to prop=imageinfo, rather than having to use timestamps.

Add img_id, oi_id, and oi_img_id
When a new version of a file is uploaded, set oi_img_id to the file's former img_id.

Add img_id, img_latest, oi_id, and oi_img_id
img will be like the table, and oldimage will be like the  table.