Fields of type File are incorrectly rendered inside a repeating block

[rogierkoppejan]

When rendering a RepeatingFieldCollection, fields of type File (image, audio, etc) have an incorrect key. More specifically, the key is set to the type of field (i.e. image), while it should be the label (i.e. my_field_name). This not only results in unexpected key names, but also overwrites previous file fields in the same block because they all have the same key.

Example, given the following block:

my_block:
    type: block
    fields:
        my_fieldset:
            fields:
                first_image:
                    type: image
                second_image:
                    type: image

This will be rendered as:

{
  "my_block": [
    {
      "image": {
        "file": "images/filename.jpg",
        "url": "http://hostname.com/files/",
        "thumbnail": "http://hostname.com/thumbs/400x300/images/filename.jpg"
      },
      "_block": "my_fieldset"
    }
  ]
}

[xiaohutai]

Fixed via #89