clean up migrations

migrations/006-add-machine-config.js

@@ -3,10 +3,10 @@
 var db = require('./db')
 
 exports.up = function (next) {
-  db.query('CREATE TABLE IF NOT EXISTS machine_configs ( ' +
+  db.multi(['CREATE TABLE IF NOT EXISTS machine_configs ( ' +
     'id serial PRIMARY KEY, ' +
     'device_fingerprint text NOT NULL, ' +
-    'data json NOT NULL )', next)
+    'data json NOT NULL )'], next)
 }
 
 exports.down = function (next) {