The summer box office continued to lack mojo, as the R-rated "Sex Tape" failed to turn on moviegoers over a weekend where "Dawn of the Planet of the Apes" maintained its rule. 20th Century Fox's science fiction sequel outmuscled a trio of new films to top the North American box office for the second-straight week with $36 million, according to studio estimates Sunday. The acclaimed sequel to 2011's reboot of the chimp franchise has now made $139 million domestically in two weeks. Its closest...