Added +2 release names for versionutils

The default value for remove_in for versionutils.deprecated is 2,
yet the names of the next two releases following Mitaka are not
defined in the _RELEASES dict. This provides the release name
for Mitaka deprecated functionality.

Change-Id: Ia5fd07d152b590d78e45f4765edef1c9aea7e526

oslo_log/tests/unit/test_versionutils.py

@@ -326,3 +326,33 @@ class DeprecatedTestCase(test_base.BaseTestCase):
 
         mock_register_opts.assert_called_once_with(
             versionutils.deprecated_opts)
+
+    @mock.patch('oslo_log.versionutils.report_deprecated_feature')
+    def test_deprecated_mitaka_plus_two(self, mock_reporter):
+
+        @versionutils.deprecated(as_of=versionutils.deprecated.MITAKA,
+                                 remove_in=+2)
+        class OutdatedClass(object):
+            pass
+        obj = OutdatedClass()
+
+        self.assertIsInstance(obj, OutdatedClass)
+        self.assert_deprecated(mock_reporter,
+                               what='OutdatedClass()',
+                               as_of='Mitaka',
+                               remove_in='Ocata')
+
+    @mock.patch('oslo_log.versionutils.report_deprecated_feature')
+    def test_deprecated_newton_plus_two(self, mock_reporter):
+
+        @versionutils.deprecated(as_of=versionutils.deprecated.NEWTON,
+                                 remove_in=+2)
+        class OutdatedClass(object):
+            pass
+        obj = OutdatedClass()
+
+        self.assertIsInstance(obj, OutdatedClass)
+        self.assert_deprecated(mock_reporter,
+                               what='OutdatedClass()',
+                               as_of='Newton',
+                               remove_in='P')

oslo_log/versionutils.py

@@ -106,6 +106,8 @@ class deprecated(object):
     KILO = 'K'
     LIBERTY = 'L'
     MITAKA = 'M'
+    NEWTON = 'N'
+    OCATA = 'O'
 
     _RELEASES = {
         # NOTE(morganfainberg): Bexar is used for unit test purposes, it is
@@ -119,6 +121,8 @@ class deprecated(object):
         'K': 'Kilo',
         'L': 'Liberty',
         'M': 'Mitaka',
+        'N': 'Newton',
+        'O': 'Ocata',
     }
 
     _deprecated_msg_with_alternative = _(