fix #1555: add waitlists_joined db column

db/migrations/20200220143251_add-waitlists-column.js

@@ -0,0 +1,13 @@
+"use strict";
+
+exports.up = function(knex) {
+  return knex.schema.table("subscribers", table => {
+    table.jsonb("waitlists_joined");
+  });
+};
+
+exports.down = function(knex) {
+  return knex.schema.table("subscribers", table => {
+    table.dropColumn("waitlists_joined");
+  });
+};