fix: Fixed sequelize-cli db:migration cannot stop when occur error

Up and Down method must return a Promise.

breaking changes: docker-hackmd cannot initialize, because db:migration will fail

lib/migrations/20160703062241-support-authorship.js

@@ -1,25 +1,29 @@
 'use strict'
 module.exports = {
   up: function (queryInterface, Sequelize) {
-    queryInterface.addColumn('Notes', 'authorship', Sequelize.TEXT)
-    queryInterface.addColumn('Revisions', 'authorship', Sequelize.TEXT)
-    queryInterface.createTable('Authors', {
-      id: {
-        type: Sequelize.INTEGER,
-        primaryKey: true,
-        autoIncrement: true
-      },
-      color: Sequelize.STRING,
-      noteId: Sequelize.UUID,
-      userId: Sequelize.UUID,
-      createdAt: Sequelize.DATE,
-      updatedAt: Sequelize.DATE
+    return queryInterface.addColumn('Notes', 'authorship', Sequelize.TEXT).then(function () {
+      return queryInterface.addColumn('Revisions', 'authorship', Sequelize.TEXT)
+    }).then(function () {
+      return queryInterface.createTable('Authors', {
+        id: {
+          type: Sequelize.INTEGER,
+          primaryKey: true,
+          autoIncrement: true
+        },
+        color: Sequelize.STRING,
+        noteId: Sequelize.UUID,
+        userId: Sequelize.UUID,
+        createdAt: Sequelize.DATE,
+        updatedAt: Sequelize.DATE
+      })
     })
   },
 
   down: function (queryInterface, Sequelize) {
-    queryInterface.dropTable('Authors')
-    queryInterface.removeColumn('Revisions', 'authorship')
-    queryInterface.removeColumn('Notes', 'authorship')
+    return queryInterface.dropTable('Authors').then(function () {
+      return queryInterface.removeColumn('Revisions', 'authorship')
+    }).then(function () {
+      return queryInterface.removeColumn('Notes', 'authorship')
+    })
   }
 }