By CHARLOTTE EBY, Courier Des Moines Bureau DES MOINES --- Democrat presidential nominee Barack Obama will head to Iowa Friday for a rally in the Des Moines area, just four days before voters are scheduled to head to the polls. The event will be open to the public, and details will be released later in the week. Obama had to cancel a planned trip to Iowa last week in order to visit his ailing grandmother in Hawaii. “Barack Obama’s campaign to change Washington has deep roots in Iowa, so it is fitting that he returns once again to remind Iowans...