Allow middlewares to be set before json-server middlewares

src/index.js

@@ -1,4 +1,11 @@
+var express = require('express')
+
 module.exports = {
-  create: require('./server'),
+  create: function () {
+    var server = express()
+    server.set('json spaces', 2)
+    return server
+  },
+  defaults: require('./defaults'),
   router: require('./router')
 }