title: Tensorflow 1.3 opencl support
body: <p>I browsed the Tensorflow code and stumbled upon OpenCL keywords several times. 
  Can TensorFlow 1.3 now be used with a non Nvidia GPU?
  Has anybody tried that? There is no mentioning in the documentation yet on this topic.
  QUESTION: if this is possible, how? Can you guide me to steps necessary?</p>