Migrate to multi branch directory structure

Also added branch_labels to .mako script.

Partially-Implements: blueprint online-schema-migrations
Change-Id: Iae8a8dd821e200f6c918b117875f58af6aedf9ed

neutron_lbaas/db/migration/alembic_migrations/script.py.mako

@@ -24,6 +24,9 @@ Create Date: ${create_date}
 # revision identifiers, used by Alembic.
 revision = ${repr(up_revision)}
 down_revision = ${repr(down_revision)}
+% if branch_labels:
+branch_labels = ${repr(branch_labels)}
+%endif
 
 from alembic import op
 import sqlalchemy as sa

neutron_lbaas/db/migration/alembic_migrations/versions/HEAD

@@ -1 +0,0 @@
-kilo

neutron_lbaas/db/migration/alembic_migrations/versions/HEADS

@@ -0,0 +1,3 @@
+130ebfdef43
+3345facd0452
+kilo

neutron_lbaas/db/migration/alembic_migrations/versions/liberty/contract/130ebfdef43_initial.py

@@ -0,0 +1,31 @@
+# Copyright 2015 OpenStack Foundation
+#
+#    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.
+
+"""Initial Liberty no-op contract revision.
+
+Revision ID: 130ebfdef43
+Revises: None
+Create Date: 2015-07-18 14:35:22.242794
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '130ebfdef43'
+down_revision = None
+branch_labels = ('liberty_contract',)
+depends_on = ('kilo',)
+
+
+def upgrade():
+    pass

neutron_lbaas/db/migration/alembic_migrations/versions/liberty/expand/3345facd0452_initial.py

@@ -0,0 +1,31 @@
+# Copyright 2015 OpenStack Foundation
+#
+#    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.
+
+"""Initial Liberty no-op expand script.
+
+Revision ID: 3345facd0452
+Revises: None
+Create Date: 2015-07-18 14:35:22.234191
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '3345facd0452'
+down_revision = None
+branch_labels = ('liberty_expand',)
+depends_on = ('kilo',)
+
+
+def upgrade():
+    pass