Add a migration to move the existing webhooks over and another migration to remove the legacy webhooks table.

data/migrations/versions/47670cbeced_migrate_existing_webhooks_to_.py

@@ -0,0 +1,22 @@
+"""Migrate existing webhooks to notifications.
+
+Revision ID: 47670cbeced
+Revises: 325a4d7c79d9
+Create Date: 2014-07-31 13:49:38.332807
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '47670cbeced'
+down_revision = '325a4d7c79d9'
+
+from alembic import op
+import sqlalchemy as sa
+
+
+def upgrade():
+    pass
+
+
+def downgrade():
+    pass