Grunt: Remove addons leftovers

Follow-up to 098221eb4a2b68540c9b655b6ba4ee9668d56148
Core: Add config property for disabling default scroll-to-top

By default, the page scrolls to the top when the suite is done. Setting
this to false will prevent that behaviour.

Fixes gh-414
Closes gh-469
CSS: Removing redundancy

Closes gh-514