Change to sub head for NB & SS
Merge branch 'new-look-and-feel' of https://github.com/SixSq/sixsq.github.com into new-look-and-feel

Conflicts:
	_layouts/article_nuvlabox_overview.html
	_layouts/article_slipstream_overview.html
Merge branch 'new-look-and-feel' of https://github.com/SixSq/sixsq.github.com into new-look-and-feel