data: addition of CMS masterclass files from DocDB

* Adds CMS masterclass files from DocDB.  (closes #67) (PR #287)

* Merge note: installation instructions amended accordingly.

Tested-by: Tibor Simko <tibor.simko@cern.ch>
docs: addition of issue stats and licence badges

Signed-off-by: Tibor Simko <tibor.simko@cern.ch>
docs: fix for licence badge style and link

Signed-off-by: Tibor Simko <tibor.simko@cern.ch>
UI: changes logo back to HTML/CSS
UI: responsiveness on "Homepage"

* (closes #76)
UI: introduces experiment images next to actions
UI: introduces breadcrumbs in pages

* (addresses #316)
UI: testimonials styling
UI: removes background colour from entrypoints
menu: adds "education","research" - rearrange