Add the possibility to separate recoverable and not recoverable errors in DelegationTokenStore

After HIVE-15090 committed we discussed it with thejas and agreed, that it would be even better if the DelegateTokenStore implementation could decide if an error is recoverable or not. Since the DelegationTokenStore is not mentioned as a Hive API it is possible to change the interface, so we could change the implementations shipped with Hive to use the new functionality, and if someone uses it's own implementation of DelegationTokenStore, then he should do the matching changes himself