Revert "use logging rather than writing to stdout directly" for collectstatic

This reverts commit 239fa61bd5bf577503be9b90830dd466194cfb55.
Added Test facility for A/B testing.
Merge branch 'nalanda-rct3' of github.com:learningequality/ka-lite into nalanda-rct3
Merge pull request #2381 from learningequality/nalanda-rct3

Nalanda rct3 to central-master