title: I want to change the base path for image of ckeditor
body: <p>I`m making the image upload system on ckeditor with carrierwave.
  But when I try to upload the image, it shows an error.</p>
  
  <p>Its because I am running my service on subdirectory '/guide'. so the path to request url is under '/guide'.
  So I want to change the base path on ckeditor, but I don`t know how to change...</p>
  
  <p><a href="https://i.stack.imgur.com/tRhwm.png" rel="nofollow noreferrer">error</a></p>
  
  <p>I want to change the request url from this</p>
  
  <p>//localhost:3000/ckeditor/pictures?&amp;CKEditor=post_content&amp;CKEditorFuncNum=1&amp;langCode=ja</p>
  
  <p>to</p>
  
  <p>//localhost:3000/guide/ckeditor/pictures?&amp;CKEditor=post_content&amp;CKEditorFuncNum=1&amp;langCode=ja</p>