agent/somcsrv/client.go
func (c *Client) Offering(hash data.HexString) (data.Base64String, error) {
	return c.requestWithPayload("api_offering", string(hash))
}
func (c *Client) Offering(hash data.HexString) (data.Base64String, error) {
	return c.requestWithPayload("api_offering", string(hash))
}
// Offering gets offering message through tor net.