ATLAS: s/ALICE/ATLAS on the "About ATLAS" page

* Replaces "ALICE" by "ATLAS" in the "About ATLAS" page text.  (PR #421)

* Merge note: substituted also all other occurrences of "alice" string,
  even inside CSS.

Co-authored-by: Tibor Simko <tibor.simko@cern.ch>