Tag the alembic migration revisions for Newton

This allows the database to be upgraded with the command:
  neutron-db-manage upgrade newton

Change-Id: I41e829a680a8fc003e7cddd18a3a6d3c059b1a6b

neutron_taas/db/migration/alembic_migration/versions/newton/contract/4086b3cffc01_rename_tenant_to_project.py

@@ -27,13 +27,16 @@ down_revision = '2ecce0368a62'
 
 from alembic import op
 import sqlalchemy as sa
-
-
 from sqlalchemy.engine import reflection
 
+from neutron.db import migration
+
 
 _INSPECTOR = None
 
+# milestone identifier, used by neutron-db-manage
+neutron_milestone = [migration.NEWTON]
+
 
 def get_inspector():
     """Reuse inspector."""

neutron_taas/db/migration/alembic_migration/versions/newton/expand/fddbdec8711a_add_status.py

@@ -25,10 +25,15 @@ revision = 'fddbdec8711a'
 down_revision = '04625466c6fa'
 
 from alembic import op
+from neutron.db import migration
 from neutron_lib import constants
 import sqlalchemy as sa
 
 
+# milestone identifier, used by neutron-db-manage
+neutron_milestone = [migration.NEWTON]
+
+
 def upgrade():
     op.add_column('tap_services', sa.Column('status', sa.String(16),
                                             server_default=constants.ACTIVE,