Update ale_agent.py
Update ale_agent.py

Small bug with mean_q corrected
omnivert/deep_q_rl,jcatw/deep_q_rl,sygi/deep_q_rl,davidsj/deep_q_rl,alito/deep_q_rl,alito/deep_q_rl,jleni/deep_q_rl,codeaudit/deep_q_rl,spragunr/deep_q_rl,jcatw/deep_q_rl,davidsj/deep_q_rl,omnivert/deep_q_rl,vvw/deep_q_rl,spragunr/deep_q_rl,jleni/deep_q_rl,codeaudit/deep_q_rl,sygi/deep_q_rl,vvw/deep_q_rl