title: Vagrant Base Box with multiple disks
body: <p>I want to create a vagrant base box that contains two disks. 
  I can't see any support for it?</p>
  
  <p>I know I can reference an existing virtual disk in the vagrant file, but i want to be able to distribute a pre-configured disk. If i can't add it to the box any other suggestions for getting a second pre-configured image attached?</p>