more fixes in Gym Ant to make reward the same as Roboschool,

apparently feet_collision_cost is not properly updated in Roboschool,
for now, disable it in pybullet too: see https://github.com/openai/roboschool/issues/63

examples/pybullet/gym/pybullet_envs/examples/enjoy_TF_AntBulletEnv_v0_2017may.py

@@ -51,6 +51,8 @@ def main():
             time.sleep(0.01)
             a = pi.act(obs)
             obs, r, done, _ = env.step(a)
+            #print("reward")
+            #print(r)
             score += r
             frame += 1
             distance=5