Adding a few example file names to directory example.

- Make it easier to understand the content of a directory by replacing X with a couple of actual example file names.
Remove item from summary that might not be covered.

Removed "- Iterate and improve in the browser."
Adding a new style for headings where we want to be able to see the background image, but still want a clue as to what the page is about. Use data-state='bgimage--reveal-activity' for this style of heading.
Merge branch 'master' of https://github.com/DrupalizeMe/drupal7-psdtotheme-series