HTML5 Multiple File upload support

[Jari Pennanen]

Django backend does not support multiple file field in HTML5, currently implemented by Chrome.

Here is excerpt of HTML5 how it is done:

<form action='#' method='post' enctype='multipart/form-data'>
  <input name='uploads' type=file multiple>
  <input type='submit'>
</form>

I have not tested what happens in Django when using above, but nevertheless there should be new form fields and model fields for this.

More details see ​blog post uploading multiple files using html5 and ​W3 File Upload State.

[Karen Tracey]

Duplicate of #12446.