Many of the banners touting free rent and other promotions have disappeared from Indianapolis-area apartment complexes. The concessions no longer are necessary as more Hoosiers look to rent, and they stay in apartments longer. Market observers say a big reason for the uptick is the subprime housing crisis and a resulting slowdown in new-home construction. “People are staying longer because it’s a little more difficult to purchase a home,” said Alexandra Jackiw, president of Buckingham Management LLC, a subsidiary of…