The new artistic director of the Young Vic in London will break the arts glass ceiling for African-Caribbeans. It's a role he has performed before in Baltimore, making theatre about police violence and experiencing the 'rage' gripping the USPortrait: Alicia Canter for the GuardianKwame Kwei-Armah's imposing face has just been splashed all over the news. Last week he was appointed artistic director of Young Vic in Lon…