The Cubs made it official with free agent Edwin Jackson, signing the pitcher to a four-year contract on Wednesday.  The deal had previously been reported to be worth $52-million.  The 29-year-old former White Sox starter will be joining his eighth club since debuting in the majors in 2003.  He made 31 starts last season with the Washington Nationals, going 10-and-11 with a 4.03 ERA.