Completed TODO
README.md tweaks after review
Add a link to the architecture doc
fullstop
ARCHITECTURE.md updates
Clustering doc review
Add a build/README.md
Obsoleted backend/README.md
Plugins README
No more Rails
Update Selenium public README.md
Updated Selenium README
Add a scheduler task for expiring old backend sessions
Fix case in I18n include
Merge branch 'master' into coveralls-master