Instantiate generic Object instead of generating random integer.

Instantiating an Object is a bit over 4x faster and guaranteed not to collide.

user> (time (dotimes [x 10000000] (rand-int Integer/MAX_VALUE)))
"Elapsed time: 2229.583833 msecs"

user> (time (dotimes [x 10000000] (Object.)))
"Elapsed time: 530.217513 msecs"