theano_tf_convert.py: use config file
theano_tf_convert.py: use config file

Use the model's existing config file instead of probing the model to
figure out the settings.

rsennrich/nematus,EdinburghNLP/nematus,rsennrich/nematus,rsennrich/nematus,EdinburghNLP/nematus,EdinburghNLP/nematus,rsennrich/nematus,EdinburghNLP/nematus,EdinburghNLP/nematus,rsennrich/nematus,EdinburghNLP/nematus,rsennrich/nematus