remove hentry from <article> in single posts, otherwise move it after h-entry

based on https://github.com/pfefferle/SemPress/commit/b137feb771c3a1de1393bdcbee6d28b1bd91109f

here are examples. the h-feed name in the scond is ugly, but that's my site's fault. otherwise everything looks good to me.

http://pin13.net/mf2/?url=http%3A%2F%2Fsnarfed.org%2F2013-10-23_oauth-dropins
http://pin13.net/mf2/?url=http%3A%2F%2Fsnarfed.org%2F