Prepare TensorFlow and Caffe sample GPU jobs.

[Tomcli]

Note: Currently GPU workloads on FfDL only works with Feature gate accelerator.

We need to prepare for some sample TensorFlow and Caffe jobs that uses GPU.

• To run TensorFlow and Caffe GPU workloads, we need to build the LCM image with bvlc/caffe:gpu and tensorflow/tensorflow:latest-gpu enable under lcm/service/lcm/container_helper_extensions.go

[Tomcli]

Preview of the sample GPU jobs are available at the gpu-dev branch.