Anyone who's ever wondered whether they have a Revolutionary War ancestor is about to get a free chance to find out. To mark the nation's upcoming 250th anniversary, the military history data site Fold3 by Ancestry is offering free access to its collection of 34 million Revolutionary War records for 250 hours, from June 27 through July 6. The promotion coincides with a renewed interest in family history surrounding America's 250th birthday. "Abo…