Fix sm integration issues (#359)

* use tensorflow.keras instead of standalone keras library

* use tf keras for inception scripts

Co-authored-by: Satish Gollaprolu <sgollapr@amazon.com>

Author: Satish615

test/resources/keras_inception.py

@@ -13,7 +13,7 @@
 import argparse
 import os
 
-import keras
+from tensorflow import keras
 import tensorflow as tf
 
 parser = argparse.ArgumentParser()

test/resources/mnist/horovod_mnist.py

@@ -15,14 +15,14 @@
 import os
 import subprocess
 
-import keras
-from keras.datasets import mnist
-from keras.models import Sequential
-from keras.layers import Dense, Dropout, Flatten
-from keras.layers import Conv2D, MaxPooling2D
-from keras import backend as K
+from tensorflow import keras
+from tensorflow.keras.datasets import mnist
+from tensorflow.keras.models import Sequential
+from tensorflow.keras.layers import Dense, Dropout, Flatten
+from tensorflow.keras.layers import Conv2D, MaxPooling2D
+from tensorflow.keras import backend as K
 import tensorflow as tf
-import horovod.keras as hvd
+import horovod.tensorflow.keras as hvd
 
 
 # Horovod: initialize Horovod.