feedback: introduced right-side tab for widget
header: stamp FIX + remove switch + img rename
fixtures: collection fixtures added
collections: experiment + collection overviews

* added “EXPERIMENTS” menu in top navigation bar
* new maincollections/experiment page at “/experiments” or
“/collections” or “/collection”
* updated collection page
records: disclaimer

* added “Disclaimer” tab on sidebar
* added Creative Common (CC) signs
vms_page: tab functionality CMS/ALICE

* tab functionality for CMS/ALICE - different content for same page
Merge branch 'pu-updates' of https://github.com/pamfilos/open-data.cern.ch into pamfilos-pu-updates