Increase timeout limit to 20 minutes for tf_cifar test to avoid tests timing out using tf 1.6.0 (aws#129)

Author: yangaws

tests/integ/test_tf_cifar.py

@@ -31,7 +31,7 @@ def __call__(self, data):
 
 
 def test_cifar(sagemaker_session, tf_full_version):
-    with timeout(minutes=15):
+    with timeout(minutes=20):
         script_path = os.path.join(DATA_DIR, 'cifar_10', 'source')
 
         dataset_path = os.path.join(DATA_DIR, 'cifar_10', 'data')