title: WEBrick error loading asset files
body: <p>When I run an instance of WEBrick server and point my browser to localhost:2000/so_question, the server throws the following errors:
  i. ERROR /some_image.jpg not found.
  ii. ERROR /jquery.min.js not found.</p>
  
  <p>sample code:</p>
  
  <pre><code>require 'webrick'; include WEBrick
  s = HTTPServer.new Port: 2000
  
  class SoQuestion &lt; HTTPServlet::AbstractServlet
  
  def do_GET req, resp
    resp.status = 200
    resp['Content-Type'] = 'text/html'
    resp.body = prep_body
  end
  
  def prep_body
    body = %(
    &lt;!DOCTYPE html&gt;
    &lt;html&gt;
    &lt;head&gt;
    &lt;title&gt;&lt;/title&gt;
    &lt;/head&gt;
    &lt;body&gt;
  )
    body &lt;&lt; '&lt;p&gt;Hello, world!&lt;/p&gt;'
    body &lt;&lt; "&lt;img src='some_image.jpg'&gt;"
    body &lt;&lt; "&lt;script src='jquery.min.js'&gt;&lt;/script&gt;"
    body &lt;&lt; '&lt;/body&gt;&lt;/html&gt;'
  end
  
  end
  
  s.mount '/so_question', SoQuestion
  trap('INT'){s.shutdown}
  s.start
  </code></pre>
  
  <p>How to fix these errors? Plz, suggest a pure-Ruby solution(no gems, plz).</p>
  
  <p>Thanks.</p>