fix: Support SQlite

Move 'unique' constraint to another statement (SQLite don't support set unique when addColumn)

lib/migrations/20150915153700-change-notes-title-to-text.js

@@ -3,12 +3,17 @@ module.exports = {
   up: function (queryInterface, Sequelize) {
     return queryInterface.changeColumn('Notes', 'title', {
       type: Sequelize.TEXT
+    }).then(function () {
+      // manual added index will be removed in sqlite
+      return queryInterface.addIndex('Notes', ['shortid'])
     })
   },
 
   down: function (queryInterface, Sequelize) {
     return queryInterface.changeColumn('Notes', 'title', {
       type: Sequelize.STRING
+    }).then(function () {
+      return queryInterface.addIndex('Notes', ['shortid'])
     })
   }
 }