fix: fixing dockerfile bug, && on both end and beginning of the line (#256)

* Fixing dockerfile bug, && on both end and beginning of the line

* Fixing gpu placement to not use session

Author: sboshin

test/resources/gpu_device_placement.py

@@ -15,12 +15,12 @@
 # https://www.tensorflow.org/programmers_guide/using_gpu
 print('-' * 87)
 print('Run GPU test.')
+tf.debugging.set_log_device_placement(True)
 with tf.device('/gpu:0'):
     a = tf.constant([1.0, 2.0, 3.0, 4.0, 5.0, 6.0], shape=[2, 3], name='a')
     b = tf.constant([1.0, 2.0, 3.0, 4.0, 5.0, 6.0], shape=[3, 2], name='b')
 c = tf.matmul(a, b)
-sess = tf.compat.v1.Session(config=tf.compat.v1.ConfigProto(log_device_placement=True))
 # Runs the op.
-print(sess.run(c))
+print(c)
 print('-' * 87)
 print('')