def convert_string_to_file(string)
      file = Tempfile.new('MG_TMP_MIME')
      file.write(string)
      file.rewind
      file
    end
def convert_string_to_file(string)
      file = Tempfile.new('MG_TMP_MIME')
      file.write(string)
      file.rewind
      file
    end
Converts MIME string to file for easy uploading to API

 @param [String] string MIME string to post to API
 @return [File] File object