Rework how posts are displayed in the modqueue:
* Rearrange post info to take up less space and to be consistent with
how posts are shown on the comments index.
* Reduce font size of approve / reject options.
* Reduce empty space around thumbnails and between posts.
* Add size info beneath thumbnails.
* Allow voting on posts.
* Use PostPresenter.preview to standardize rendering of thumbnails. This
adds parent/child borders, tooltips, and data attributes.
