Fix TensorFlow API usage to be compatible for v0.x and v1.x

[TITAN-PyCompat]

Dear developers,

I found some detrimental usages of TensorFlow API which might lead to severe problems like crashes when users use different version of tensorflow.

As I fixed in the code: the APIs tf.image_summary, tf.scalar_summary, tf.merge_summary, tf.histogram_summary,tf.merge_all_summaries have been deprecated in tf v0.12.0 and been deleted since v1.0.0. It's better to change to the following APIs tf.summary.image, tf.summary.scalar, tf.summary.merge, tf.summary.histogram, tf.summary.merge_all