Support server-side plugins.

[pilwon]

• Turn auth, socketio, winston related code into auto-discoverable plugins.
• project.json:

{
  "server": {
    "plugins": {
      "auth": true,
      "auth-facebook": true,
      "auth-google": true,
      "auth-twitter": true,
      "socketio": true,
      "winston": true
    }
  }
}

[pilwon]

Plugins

• ultimate-admin: Admin plugin
• ultimate-auth: Auth plugin
• ultimate-auth-facebook: Facebook Auth plugin
• ultimate-auth-google: Google Auth plugin
• ultimate-auth-twitter: Twitter Auth plugin
• ultimate-socketio: Socket.io plugin
• ultimate-winston: Winston plugin