Fix bug "AttributeError: 'generator' object has no attribute 'next'"

1. the bug:
   Captured traceback:
   ~~~~~~~~~~~~~~~~~~~
	Traceback (most recent call last):

	File "/opt/stack/freezer/freezer/tests/unit/scheduler/test_utils.py", line 53, in test_find_config_files_path
	ret = utils.find_config_files(temp_path)

	File "/opt/stack/freezer/freezer/scheduler/utils.py", line 53, in find_config_files
	for fname in os.walk(expanded_path).next()[2]:

	AttributeError: 'generator' object has no attribute 'next'

2. fix:
To get iterobject next element  is  changed to next(iterobject,defalt) in python3.x.

Change-Id: I558bbfecb4a9670a10b1fc649821d88619b7917c

freezer/scheduler/utils.py

@@ -50,7 +50,7 @@ def find_config_files(path):
         return [expanded_path]
     file_list = []
     if os.path.isdir(expanded_path):
-        for fname in os.walk(expanded_path).next()[2]:
+        for fname in next(os.walk(expanded_path))[2]:
             if CONFIG_FILE_EXT.upper() == os.path.splitext(fname)[1].upper():
                 file_list.append('{0}/{1}'.format(expanded_path, fname))
         return file_list

freezer/tests/unit/scheduler/test_utils.py

@@ -44,8 +44,8 @@ class TestUtils(unittest.TestCase):
         temp.close()
         self.assertFalse(os.path.exists(temp.name))
 
-    @unittest.skipIf(sys.version_info.major == 3,
-                     'Not supported on python v 3.x')
+    # @unittest.skipIf(sys.version_info.major == 3,
+    #                 'Not supported on python v 3.x')
     def test_find_config_files_path(self):
         temp = tempfile.NamedTemporaryFile('wb', delete=True,
                                            suffix='.conf')