When multi-talented guitarist and singer Joe Louis Walker returns to the Jazz and Heritage Festival after an eleven year absence, he will be preaching from a different musical pulpit. In 1985, Walker played Jazz Fest as a member of gospel group The Spiritual Corinthians, but hearing the myriad sounds pulsing across the fairgrounds inspired Walker to return to his roots. “I wanted to play blues,” Walker recently said by phone from California. “I wanted to play all kinds of music, really. I jus...