Polish /{item,tag,lend}/<id> pages.

Add links to each page leading to the update/edit and delete pages. All links
are contained within `p.controls` tags.

Improve wording of headlines and paragraphs. For example, make header state
"Notes About This Tag" instead of "Notes".

Convert some headers into <p> tags. Also show less information by default. For
example, only show "tags attached to this item" if tags are actually attached to
that item. These two changes make it much easier to find useful information
about an item. Less time is spent wading through useless information and
excessive headers.