Fixing JSHint errors
Fixing JSHint errors

mcanthony/PhysicsJS,Nayar/PhysicsJS,Luwdo/PhysicsJS,griever989/PhysicsJS,Luwdo/PhysicsJS,jpellerin/PhysicsJS,VANITAX/PhysicsJS,VANITAX/PhysicsJS,wellcaffeinated/PhysicsJS,pietro909/PhysicsJS,Rawneed/PhysicsJS,rohit765/PhysicsJS,eric-seekas/PhysicsJS,eric-seekas/PhysicsJS,mcanthony/PhysicsJS,Nayar/PhysicsJS,haithemaraissia/PhysicsJS,griever989/PhysicsJS,haithemaraissia/PhysicsJS,rohit765/PhysicsJS,aldeed/PhysicsJS,aldeed/PhysicsJS,jpellerin/PhysicsJS,Rawneed/PhysicsJS,wellcaffeinated/PhysicsJS,pietro909/PhysicsJS