fix(search): ensure consistent html in search results

This implements some of the changes discussed in #2314:

1. last mod and number of hits are on the same line and always shown
2. There is a class around the last mod string so it can be
hidden/replaced by an icon
3. All items in the resultBody returned by the event are wrapped in
`<dd>` tags to ensure validity. They get their array key as class
4. There is still a wrapper div around each result for styling purposes