In a music industry so fickle that some groups don’t make it 50 days after releasing a recording, the mighty Tower of Power will celebrate its 50th anniversary next year. The celebrated ambassadors of Oakland soul have been setting stages on fire since the group formed in 1968, through a string of memorable 1970s hits (“You’re Still a Young Man,” “So Very Hard to Go,” “What is Hip?”), a legendary association with famed con...