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/20160607060246-support-revision.js

@@ -1,24 +1,26 @@
 'use strict'
 module.exports = {
   up: function (queryInterface, Sequelize) {
-    queryInterface.addColumn('Notes', 'savedAt', Sequelize.DATE)
-    queryInterface.createTable('Revisions', {
-      id: {
-        type: Sequelize.UUID,
-        primaryKey: true
-      },
-      noteId: Sequelize.UUID,
-      patch: Sequelize.TEXT,
-      lastContent: Sequelize.TEXT,
-      content: Sequelize.TEXT,
-      length: Sequelize.INTEGER,
-      createdAt: Sequelize.DATE,
-      updatedAt: Sequelize.DATE
+    return queryInterface.addColumn('Notes', 'savedAt', Sequelize.DATE).then(function () {
+      return queryInterface.createTable('Revisions', {
+        id: {
+          type: Sequelize.UUID,
+          primaryKey: true
+        },
+        noteId: Sequelize.UUID,
+        patch: Sequelize.TEXT,
+        lastContent: Sequelize.TEXT,
+        content: Sequelize.TEXT,
+        length: Sequelize.INTEGER,
+        createdAt: Sequelize.DATE,
+        updatedAt: Sequelize.DATE
+      })
     })
   },
 
   down: function (queryInterface, Sequelize) {
-    queryInterface.dropTable('Revisions')
-    queryInterface.removeColumn('Notes', 'savedAt')
+    return queryInterface.dropTable('Revisions').then(function () {
+      return queryInterface.removeColumn('Notes', 'savedAt')
+    })
   }
 }