fix up dvr api def exceptions

Commit I6d98e83287833882515240d7db1faa4a1deb7da1 rehomed the DVR
API def into neutron-lib, but:
- The DVRMacAddressNotFound exception was never rehomed. While not used
externally today [1], it's foreseeable that implementations of the
extension will need it.
- The exception message used in HostMacAddressGenerationFailure of the
rehome patch mentions "DVR". This should not be the case as the
HostMacAddressGenerationFailure is generic in nature.

[1] http://codesearch.openstack.org/?q=DVRMacAddressNotFound

Change-Id: I88e1aa2acf22389f69cb7d5704c80a5eb72a9bbe

neutron_lib/exceptions/__init__.py

@@ -522,7 +522,7 @@ class HostMacAddressGenerationFailure(ServiceUnavailable):
 
     :param host: The host MAC address generation failed for.
     """
-    message = _("Unable to generate unique DVR mac for host %(host)s.")
+    message = _("Unable to generate unique mac for host %(host)s.")
 
 
 class NetworkMacAddressGenerationFailure(ServiceUnavailable):

neutron_lib/exceptions/dvr.py

@@ -0,0 +1,21 @@
+# Copyright (c) 2014 OpenStack Foundation.  All rights reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+from neutron_lib._i18n import _
+from neutron_lib import exceptions
+
+
+class DVRMacAddressNotFound(exceptions.NotFound):
+    message = _("Distributed Virtual Router Mac Address for "
+                "host %(host)s does not exist.")