fix #18: inverse the coding and shebang line

examples/rewards/forward_progress.py

@@ -1,5 +1,5 @@
-# -*- coding: utf-8 -*-
 #!/usr/bin/env python
+# -*- coding: utf-8 -*-
 """Demonstrate how the reward function that measures how much a robot has moved forward increases / decreases based on
 the robot velocity. Use the arrow keys on your keyboard to move the robot, and observe how the computed reward value
 changes.