Get functional/tests.py running under py3

Note that you need a pretty recent eventlet to pick up
https://github.com/eventlet/eventlet/commit/f0bc79e

Change-Id: I6b006b972e7431c406039f4e0f6890a8f74a4432

.unittests

@@ -1,6 +1,6 @@
 #!/bin/bash
 
-TOP_DIR=$(python -c "import os; print os.path.dirname(os.path.realpath('$0'))")
+TOP_DIR=$(python -c "import os; print(os.path.dirname(os.path.realpath('$0')))")
 
 python -c 'from distutils.version import LooseVersion as Ver; import nose, sys; sys.exit(0 if Ver(nose.__version__) >= Ver("1.2.0") else 1)'
 if [ $? != 0 ]; then