def set_form_data(params, sep = '&')
      self.body = params.map {|k,v| "#{urlencode(k.to_s)}=#{urlencode(v.to_s)}" }.join(sep)
      self.content_type = 'application/x-www-form-urlencoded'
    end
def set_form_data(params, sep = '&')
      self.body = params.map {|k,v| "#{urlencode(k.to_s)}=#{urlencode(v.to_s)}" }.join(sep)
      self.content_type = 'application/x-www-form-urlencoded'
    end
Set header fields and a body from HTML form data.
 +params+ should be a Hash containing HTML form data.
 Optional argument +sep+ means data record separator.

 This method also set Content-Type: header field to
 application/x-www-form-urlencoded.