Move some plugins into their own repo

- post_images and permalink_dated
Squashed 'plugins/custom/permalink_dated/' content from commit 1258b52

git-subtree-dir: plugins/custom/permalink_dated
git-subtree-split: 1258b52558074e4dc0d59e1c121d96dc71b53af8
Merge subtree 'permalink_dated'

Using path prefix:
	plugins/custom/permalink_dated

From remote at HEAD:
	https://github.com/jmeosbn/permalink_dated
Squashed 'plugins/custom/post_images/' content from commit 3dfa698

git-subtree-dir: plugins/custom/post_images
git-subtree-split: 3dfa69815856e10f96397608d2cddc1664fbffd9
Merge subtree 'post_images'

Using path prefix:
	plugins/custom/post_images

From remote at HEAD:
	https://github.com/jmeosbn/post_images
Update google group link for rss feed
Use yahoo pipes to convert rss to json
Use separate callback for each 'linkroll'

- Allows additional (async) feeds to be used
Remove extra 'archive' link
Re-enable group RSS feed in sidebar
Use CSS to truncate RSS titles