make python 3 the default for tox.ini

This patch is part of the community goals to enable python 3 first, and
only use python 2 when explict.

To do so, this patch:
- Makes python 3 the default env for non py27 tox targets.
- Addresses any py3 changes in the code.

Change-Id: Iab52979bb720a8df8924108093e5119922622cb9

tox.ini

@@ -26,7 +26,7 @@ setenv = {[testenv]setenv}
 commands = false
 
 [testenv:functional]
-basepython = python2.7
+basepython = python3
 setenv = {[testenv]setenv}
          {[testenv:common]setenv}
          OS_TEST_PATH=./vmware_nsxlib/tests/functional
@@ -36,7 +36,7 @@ deps =
   -r{toxinidir}/vmware_nsxlib/tests/functional/requirements.txt
 
 [testenv:dsvm-functional]
-basepython = python2.7
+basepython = python3
 setenv = {[testenv]setenv}
          OS_SUDO_TESTING=1
          OS_FAIL_ON_MISSING_DEPS=1
@@ -53,6 +53,7 @@ sitepackages = True
 commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [testenv:pep8]
+basepython = python3
 deps =
   {[testenv]deps}
 commands =
@@ -69,6 +70,7 @@ deps = -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/re
 commands = bandit -r vmware_nsxlib -n 5 -ll
 
 [testenv:cover]
+basepython = python3
 commands =
   python setup.py test --coverage --coverage-package-name=vmware_nsxlib --testr-args='{posargs}'
   coverage report
@@ -77,6 +79,7 @@ commands =
 commands = {posargs}
 
 [testenv:docs]
+basepython = python3
 commands = sphinx-build -W -b html doc/source doc/build/html
 
 [flake8]

vmware_nsxlib/v3/exceptions.py

@@ -42,7 +42,7 @@ class NsxLibException(Exception):
 
     if six.PY2:
         def __unicode__(self):
-            return unicode(self.msg)
+            return unicode(self.msg) if six.PY2 else self.msg  # noqa
 
     def __str__(self):
         return self.msg