HBO has released the official trailer and announced the premiere date for Paterno. The HBO Films presentation debuts Saturday, April 7 at 8 PM. Starring Al Pacino in the title role, the drama centers on Penn State's Joe Paterno in the aftermath of the Jerry Sandusky sexual abuse scandal. After becoming the winningest coach in college football history, Paterno's legacy is challenged and he is forced to face questions of institutional failure in regard to the…