AddtionalInformationForm and RTF upload

Ability to upload RTF files from the newly created AddtionalInformationForm

  - RTF attachment upload
  - Attachment deletion
  - Attachment replacement
  - Claim#miscellaneous information is set to nil when
    AddtionalInformationForm#has_miscellaneous information is
    set to false
  - AddtionalInformationForm validates only RTF and plain text files can be attached to the claim

Blockers:
  - S3 credentials