Chris Willman Senior Music Writer and Chief Music Critic The 50th anniversary celebration for the Roxy in West Hollywood this September is picking up some added components, including an additional appearance by Neil Young and Crazy Horse; a recreation by Stephen Marley of his father Bob Marley’s “Live at the Roxy” album; and a compilation album that will draw on performances from the nightclub’s five-decade history. Young was already announced to appear at the Roxy on Sept. 20, the 50th anniversary of the night he officially opened the club with a multi-night engagement.