Support for uploaded files in HTTP dumps

[butschster]

No description provided.

[Kreezag]

@butschster We need to use the same attachment format as we have for SMTP event

For now http dump returns payload.files with the format

Smtp attachment has different format:

{
          uuid: attachment.uuid,
          name: attachment.name,
          size: attachment.size,
          mime: attachment.mime,
          path: attachment.path
}

SMTP attachment also has his own request url: [site]/api/smtp/${id}/attachments