title: How to send proxy username and password with RestClient Ruby gem
body: <p>I'm using RestClient gem for a post request according to the documentation we can add proxy , but in my case proxy URL itself has authentication, how to achieve it with Restclient Gem</p>
  <pre><code>RestClient.proxy = &quot;someurl&quot;
  RestClient.proxy_user_name = ??
  RestClient.proxy_password = ??
  
  request = RestClient::Request.new(
      :method =&gt; :post,
      :url =&gt; 'some_url',
      :user =&gt; '123',
      :password =&gt; '123',
      :payload =&gt; {
          :multipart =&gt; true,
          :file =&gt; File.new(&quot;somepath&quot;, 'rb')
     }
  )
  response = request.execute
  </code></pre>