Make it possible to run testing epochs without holdout data.
Make it possible to run testing epochs without holdout data.

codeaudit/deep_q_rl,codeaudit/deep_q_rl,jcatw/deep_q_rl,omnivert/deep_q_rl,omnivert/deep_q_rl,udibr/deep_q_rl,udibr/deep_q_rl,sygi/deep_q_rl,spragunr/deep_q_rl,alito/deep_q_rl,jleni/deep_q_rl,davidsj/deep_q_rl,alito/deep_q_rl,jleni/deep_q_rl,sygi/deep_q_rl,tmylk/deep_q_rl,spragunr/deep_q_rl,tmylk/deep_q_rl,davidsj/deep_q_rl,jcatw/deep_q_rl,vvw/deep_q_rl,vvw/deep_q_rl