Gun moves faster

The gun moves faster now. In fact the gun moves as fast as the aliens.

src/game.rb

@@ -11,7 +11,7 @@ def start
         addAlien(Alien.new({:location => Vector.new(x,y), :moveStrategy => @strategy}))
       end
     end
-    @gun = Gun.new({:moveStrategy => EventedMoveStrategy.new})
+    @gun = Gun.new({:moveStrategy => EventedMoveStrategy.new(Vector.new(3,0))})
     addGun(@gun)
   end
 

src/movement.rb

@@ -15,8 +15,8 @@ def notify(event)
 end
 
 class EventedMoveStrategy < MovementStrategy
-  def initialize
-    @displacement = Vector.new(1,0)
+  def initialize(displacement = Vector.new(1,0))
+    @displacement = displacement
     @events = []
   end