Add Icehouse no-op migration

This migration marks the database migration timeline milestone for
Icehouse.

Change-Id: I8be0322843e506c07e83dc4ba1c135f36a6e2505

neutron/db/migration/alembic_migrations/versions/HEAD

@@ -1 +1 @@
-5ac1c354a051
+icehouse

neutron/db/migration/alembic_migrations/versions/icehouse_release.py

@@ -0,0 +1,42 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+#
+# Copyright 2014 Yahoo! Inc.
+#
+#    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.
+#
+
+"""icehouse
+
+Revision ID: icehouse
+Revises: 5ac1c354a051
+Create Date: 2013-03-28 00:00:00.000000
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = 'icehouse'
+down_revision = '5ac1c354a051'
+
+# Change to ['*'] if this migration applies to all plugins
+
+migration_for_plugins = ['*']
+
+
+def upgrade(active_plugins=None, options=None):
+    """A no-op migration for marking the Icehouse release."""
+    pass
+
+
+def downgrade(active_plugins=None, options=None):
+    """A no-op migration for marking the Icehouse release."""
+    pass