def delete!(headers = {})
      raise "Cannot delete #{rdf_subject}, does not exist." unless exist?
      headers['If-Match'] ||= etag
      response = make_request(:delete, nil, headers)
      @http_headers = nil
      response
    end
def delete!(headers = {})
      raise "Cannot delete #{rdf_subject}, does not exist." unless exist?
      headers['If-Match'] ||= etag
      response = make_request(:delete, nil, headers)
      @http_headers = nil
      response
    end
Sends DELETE request to the resource's #rdf_subject via #ldp_connection.
 Headers can be passed in. Default HTTP headers are:

    If-Match: "#{etag}" (uses idempotent put if an Entity Tag is cached)