Use unittest2 where available, to support python <2.7

tests/api_versions/test_v1.py

@@ -1,3 +1,6 @@
+try:
+    import unittest2 as unittest
+except ImportError:
     import unittest
 from tests import test_albums, test_photos, test_tags
 

tests/api_versions/test_v2.py

@@ -1,3 +1,6 @@
+try:
+    import unittest2 as unittest
+except ImportError:
     import unittest
 from tests import test_base, test_albums, test_photos, test_tags
 

tests/test_albums.py

@@ -1,3 +1,6 @@
+try:
+    import unittest2 as unittest
+except ImportError:
     import unittest
 import openphoto
 import test_base

tests/test_base.py

@@ -1,5 +1,8 @@
 import sys
 import os
+try:
+    import unittest2 as unittest
+except ImportError:
     import unittest
 import logging
 import openphoto

tests/test_config.py

@@ -1,3 +1,6 @@
+try:
+    import unittest2 as unittest
+except ImportError:
     import unittest
 import os
 import shutil

tests/test_framework.py

@@ -1,3 +1,6 @@
+try:
+    import unittest2 as unittest
+except ImportError:
     import unittest
 import logging
 import openphoto

tests/test_photos.py

@@ -1,3 +1,6 @@
+try:
+    import unittest2 as unittest
+except ImportError:
     import unittest
 import openphoto
 import test_base

tests/test_tags.py

@@ -1,3 +1,6 @@
+try:
+    import unittest2 as unittest
+except ImportError:
     import unittest
 import openphoto
 import test_base