IGNITE-4022 IgniteServices soesn't throw an exception if there are no server nodes

[V.Pyatkov]

Please, check my PA:

https://issues.apache.org/jira/browse/IGNITE-4022
https://github.com/apache/ignite/pull/1728

I think, test is not need. Because the suggestion will not be affect o
logic.
But I want have listened someone's mind.

--
Vladislav Pyatkov