TensorFlow APIs compatibility problems

[TITAN-PyCompat]

Hi,

I noticed some TensorFlow API usage in your code might lead to crash on early version.
Some API appeared only in tf v1.0 like tf.global_variables_initializer, tf.local_variables_initializer, tf.summary.merge_all and so on.

I made some patches for these APIs in #21

And I noticed some issues asked about tf.concat. It's another problems I found too. The paramter sequence/name has changed since tf v1.0. If you need, I can made some patches too.

I know it's a old problem, maybe you don't want to be compatible with too old versions. But it's also a compatibility problem right? @burness @soloice

Look forward to your reply, Thanks!