Rename option 'displayBadges' to 'badgeClassNames'

displayBadges sounds like it's a boolean setting. What this setting
really is is a list of ItemIds and (non-optional) CSS class names.

Badges that are not in this array stil get rendered as
class="badge-Q101", for example.

Change-Id: Ic16f0e885f1320331adfa76bc725566bee18e704
Merge "Rename option 'displayBadges' to 'badgeClassNames'"