Possible disqus fix

I noticed that around line ~380 when adding disqus comments to pages, it checks to see if we are looking at *index* or *all_posts*, while the blogger may have changed the index/all_posts pages away from their default names. I've proposed a fix for this. I honestly don't know what `${filename%.*.*}` does, but it seems to strip off the extension. I'm pretty sure it is unnecessary.