Add Python 3.5 functional tests in tox.ini

Add Python 3.5 functional tests tox envlist, this is
needed by python 3.5 functional tests Jenkins job.

Change-Id: I1bba877fcc2c1f2140cbbba2bc6e6c20d7972615

tools/pretty_tox3.sh

@@ -2,8 +2,14 @@
 
 TESTRARGS=$1
 
+if [ $OS_TEST_PATH = './nova/tests/functional' ]; then
+    blacklist_file=tests-functional-py3.txt
+else
+    blacklist_file=tests-py3.txt
+fi
+
 if [ -z "$TESTRARGS" ]; then
-    ostestr --blacklist_file tests-py3.txt
+    ostestr --blacklist_file $blacklist_file
 else
     ostestr -r "$TESTRARGS"
 fi