Added migration script

migrations/versions/add_cancelled_status.py

@@ -0,0 +1,19 @@
+"""
+
+Revision ID: add_cancelled_status
+Revises: 84c3b6eb16b3
+Create Date: 2018-07-31 13:34:00.018447
+
+"""
+from alembic import op
+
+revision = 'add_cancelled_status'
+down_revision = '84c3b6eb16b3'
+
+
+def upgrade():
+    op.execute("INSERT INTO notification_status_types (name) VALUES ('cancelled')")
+
+
+def downgrade():
+    pass