Changed Tank.move() to Tank.move_tank().  Added locomotive_entity
to Tank and added code to create Locomotion instance in Tank
constructor as Tank.locomotive_entity.  Removed Tank.MOVE_AMMOUNT
and replaced with Tank.locomotive_entity.speed.

Need to change Tank.move_tank to query environment for location
of other tanks, rather than pass the poisiton of the other tanks
to the method.  Need to move the Tank.can_move function to the
Environment class.

 On branch transitory
  Changes to be committed:
	modified:   TankWars/src/com/amphibian/tank/Locomotion.java
	modified:   TankWars/src/com/amphibian/tank/Tank.java
	modified:   TankWars/src/com/example/tankwars/TankWars.java