title: Swagger ui not working properly when using grape with versions
body: <p>If I load the content of '<a href="http://local.myproject:3000/api/swagger" rel="nofollow">http://local.myproject:3000/api/swagger</a>'</p>
  
  <p>The api endpoints are shown as '/api/0.1/activities.json' despite the fact that my version is 'V1'</p>
  
  <pre><code>version 'v1', using: :path do
    mount TheLocker::Ping
    ...
  </code></pre>
  
  <p>Exactly by this reason when I push the 'Try it out!' button on the 'swagger ui' the request can't be executed because the version part of the api is not matching the actual one.</p>
  
  <p>This is part of the message the swagger UI is displaying:</p>
  
  <pre><code>"No route matches [GET] &amp;quot;/api/0.1/activities.json&amp;quot;"
  </code></pre>