Remove noMargins and the need for addArticleClass()

Also set isOverlay to false (it was adding a .content div to many
special pages) and prepare for its removal.

Change-Id: Ie77849e636a4d7420cabae88ef7fffd9a6f85b04
Standardize the hamburger and remove isOverlay (#375)

isOverlay is not needed anymore because all pages are supposed to have
the hamburger. Articles have a searchbox, special pages have a heading.

Change-Id: Ie43b568221a067a0eaf2923bfc3a779bb8ca21ca
Merge changes Ie43b5682,Ie77849e6

* changes:
  Standardize the hamburger and remove isOverlay (#375)
  Remove noMargins and the need for addArticleClass()