Remove unnecessary tags wrapping disqus

`{block:Permalink}`

* tag doesn't exist: http://www.tumblr.com/docs/en/custom_themes
* already within a `{block:PermalinkPage}` block tag

`{block:Posts}`

* already within a `{block:Posts}` block tag

`{block:Date}`

* no Date tags are used within this block, thus tag is un-necessary

Also remove whitespace.