With the Boston Globe’s contract with newsroom and business employees set to expire at the end of the year, the paper has hired a law firm with a reputation for taking a hard line on media unions when it comes to contract talks. In a memo to members last week, the Boston Newspaper Guild, which says it represents about 600 workers at the Boston Globe and Boston.com, said the company recently hired law firm Jones Day, saying the firm is “known for union-busting in the media industry.” The…