refactor migration

lib/migrate.js

@@ -0,0 +1,19 @@
+const path = require('path')
+const migrate = require('migrate')
+
+const options = require('./options')
+
+const migrateDir = path.resolve(__dirname, '..', 'migrations')
+const migration = migrate.load(options.migrateStatePath, migrateDir)
+
+module.exports = {run}
+
+function run () {
+  return new Promise((resolve, reject) => {
+    migration.up(err => {
+      if (err) return reject(err)
+      return resolve(0)
+    })
+  })
+}
+