Serbian translation completed (app/locale/sr.coffee). (#4801)
Serbian translation completed (app/locale/sr.coffee). (#4801)

* Serbian translation completed (app/locale/sr.coffee).

* Improved Serbian translation (app/locale/sr.coffee).

codecombat/codecombat,jeremiahyan/codecombat,javatlacati/codecombat,codecombat/codecombat,javatlacati/codecombat,codecombat/codecombat,codecombat/codecombat,jeremiahyan/codecombat,jeremiahyan/codecombat,javatlacati/codecombat,javatlacati/codecombat,codecombat/codecombat,javatlacati/codecombat,jeremiahyan/codecombat