Border fixes + Comments and Quote consistency.

* Fixing further Danbooru changes to borders. All images always have a border and it's just transparent when not in use. Custom tags have been updated to work with this potentially transparent border.
* The 2px border that sort of padded the image placeholders is now gone so users using 3px wide borders will sometimes end up with no blank space between 2 images with status and custom tag borders. Debating whether to do anything about this...?
* Changed the double quotes in the new CSS stuff to single quotes in order to match the current scheme and avoid escaping quotes.