Update copyright year from 2019 to 2020
Update copyright year from 2019 to 2020

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