[tune] Tweaks to Trainable and Verbosity (#2889)

docker/examples/Dockerfile

@@ -6,5 +6,6 @@ FROM ray-project/deploy
 RUN conda install -y numpy
 RUN apt-get install -y zlib1g-dev
 RUN pip install gym[atari] opencv-python==3.2.0.8 tensorflow lz4 keras
+RUN pip install -U h5py  # Mutes FutureWarnings
 RUN pip install --upgrade git+git://github.com/hyperopt/hyperopt.git
 RUN conda install pytorch-cpu torchvision-cpu -c pytorch