Problem: We need a way to synchronize a halt to block production to allow for upgrades across breaking changes

Solution: Created `MigrationElection`

bigchaindb/common/schema/transaction_migration_election_v2.0.yaml

@@ -0,0 +1,44 @@
+# Copyright BigchainDB GmbH and BigchainDB contributors
+# SPDX-License-Identifier: (Apache-2.0 AND CC-BY-4.0)
+# Code is Apache-2.0 and docs are CC-BY-4.0
+
+---
+"$schema": "http://json-schema.org/draft-04/schema#"
+type: object
+title: Migration Election Schema - Propose a halt in block production to allow for a version change
+required:
+- operation
+- asset
+- outputs
+properties:
+  operation:
+    type: string
+    value: "MIGRATION_ELECTION"
+  asset:
+    additionalProperties: false
+    properties:
+      data:
+        additionalProperties: false
+        properties:
+          seed:
+            type: string
+    required:
+    - data
+  outputs:
+    type: array
+    items:
+      "$ref": "#/definitions/output"
+definitions:
+  output:
+    type: object
+    properties:
+      condition:
+        type: object
+        required:
+          - uri
+        properties:
+          uri:
+            type: string
+            pattern: "^ni:///sha-256;([a-zA-Z0-9_-]{0,86})[?]\
+              (fpt=ed25519-sha-256(&)?|cost=[0-9]+(&)?|\
+              subtypes=ed25519-sha-256(&)?){2,3}$"