NASHVILLE -- The seven candidates vying to become Nashville"s next mayor have spent a combined $12.5 million on their bids -- the equivalent of $43 for every registered voter in Music City.Voters go to the polls Thursday to choose among Councilwoman Megan Barry, attorney Charles Robert Bone, hedge fund manager David Fox, real estate mogul Bill Freeman, Criminal Court Clerk Howard Gentry, charter school founder Jeremy Kane and...