Fix platform display in places where it was broken by ff8dfd43d86b.

On Fri, Oct 17, 2014 at 01:10:08AM -0700, Mathieu Agopian wrote:
>> @@ -5,7 +5,7 @@
>>          {{ file.pretty_filename() }}</a>
>>      </td>
>>      <td>{{ file.size|filesizeformat }}</td>
>> -    <td>{{ form.platform }}</td>
>> +    <td>{{ form.get_platform_display() }}</td>
>
>I'm pretty sure this shouldn't be changed, it's the form field.

Hm. Yeah, I thought I'd reverted that change.