title: Ruby Grape encoding issue for Multipart-form data with string parameter
body: <p>I'm build API server with grape and android client.</p>
  
  <p>When I make post API for upload content and image,
  confront to encoding issue.</p>
  
  <p>I sent message and image to server using 'utf-8' encoding,
  but server recognized message using 'ascii-8bit' encoding.</p>
  
  <p>I tested string information using behind code.</p>
  
  <pre><code>puts "DEBUG ---- content : #{params[:content].unpack("H*")}"
    puts "DEBUG ---- content : #{params[:content].encoding}"
    puts "DEBUG ---- content2 : #{"테스트테스트".unpack("H*")}"
    puts "DEBUG ---- content2 : #{"테스트테스트".encoding}"
  </code></pre>
  
  <p>The result is</p>
  
  <pre><code>DEBUG ---- content : ["ed858cec8aa4ed8ab8ed858cec8aa4ed8ab8"]
  DEBUG ---- content : ASCII-8BIT
  DEBUG ---- content2 : ["ed858cec8aa4ed8ab8ed858cec8aa4ed8ab8"]
  DEBUG ---- content2 : UTF-8
  </code></pre>
  
  <p>so this two strings are having same data, but miss understand on server.</p>
  
  <p>Thank you for your advice.</p>
  
  <p>Tae-ho.</p>