Compatibility with TensorFlow r1.3

[s1gm01d]

It would be great if the framework becomes compatible with the new release of TensorFlow (r1.3) since I was trying to load the library, and I got an error in the installation test due to incompatibilities with that version.

[lixikun]

hi,you just modify the imports in file helper.py , the path is seq2seq/seq2seq/contrib/seq2seq/helper.py. I has tested in tensorflow 1.4,and the test result is ok!

from tensorflow.python.ops.distributions import bernoulli
from tensorflow.python.ops.distributions import categorical

[slgobinath]

Hi,
I confirm the compatibility with Tensorflow 1.4 (according to the unit test result) after the changes suggested by @lixikun. The required changes are nicely explained in #285.