Make testing scripts python3.x compatible

Update run_tests/*.py to use six based isomorphisms and print function
from __future__ module.
diff --git a/tools/run_tests/run_tests_matrix.py b/tools/run_tests/run_tests_matrix.py
index 4742245..191228e 100755
--- a/tools/run_tests/run_tests_matrix.py
+++ b/tools/run_tests/run_tests_matrix.py
@@ -30,6 +30,8 @@
 
 """Run test matrix."""
 
+from __future__ import print_function
+
 import argparse
 import multiprocessing
 import os