Fixed bad API call to jQuery.atr()

Not sure if this problem still exists upstream, but the buggy version makes '<a className="close"...' instead of '<a class="close"...'
Wrap data attributes in single quotes

To avoid breakage when passing along JSON serialized data.
add new test app folders to .gitignore
fix display_with on nil issue

Fix an issue that wasn’t applying the helper method to a value if it
started out as nil