Add func3 tox environment for functional testing with Python 3.

It's the same as func, but runs functional tests with Python 3.
One issue was fixed in ironic_inspector.test.functional.

Change-Id: I6a081ad2ca8857018c6b531ed82182aab0ccca4d

ironic_inspector/test/functional.py

@@ -171,7 +171,8 @@ def mocked_server():
         conf_file = os.path.join(d, 'test.conf')
         db_file = os.path.join(d, 'test.db')
         with open(conf_file, 'wb') as fp:
-            fp.write(CONF % {'db_file': db_file})
+            content = CONF % {'db_file': db_file}
+            fp.write(content.encode('utf-8'))
 
         with mock.patch.object(utils, 'check_auth'):
             with mock.patch.object(utils, 'get_client'):

tox.ini

@@ -27,6 +27,11 @@ basepython = python2.7
 commands =
     python -m ironic_inspector.test.functional
 
+[testenv:func3]
+basepython = python3.4
+commands =
+    python3 -m ironic_inspector.test.functional
+
 [testenv:genconfig]
 envdir = {toxworkdir}/venv
 commands =