A Philadelphia man was charged with vehicular homocide Friday for allegedly causing a fatal crash on the Schuylkill Expressway in Montgomery County last month.   Investigators say Shamsuddin Hasan was high on the club drug Ecstasy as his Jeep Grand Cherokee smashed into another vehicle driven by Daniel Chong.   The rear end crash pushed Chong's car into a concrete median barrier.  He suffered severe head injuries and died 15 hours later.   Hasan received only minor injuries.   He is being held at Montgomery County Prison on $500,000 bail.