OAS genocide

Removed references to OAS in JS/HTML/CSS, and tidied up the class names

Also created more sensible switches

 * **AdvertsSwitch**: master switch for all ads
 * **StandardAdvertsSwitch**: switch for things like inline ads, top banner, mpu
 * **CommercialComponentsSwitch**: switch for commercial components
 * **VideoAdvertsSwitch**: switch for, err, video ads