We don't use custom names and the only place where custom method option
is used it provides the default name and can be omitted.
Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>
`Get` method of `Container` contract returns binary session token, key and
signature along with container.
Provide `Signature`, `PublicKey` and `SessionToken` getters from `GetValues`
structure. Parse and set all values in `Client.Get` methods.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
