[9] RFR: 8075297: Tests for RFEs 4515853 and 4745056

[Artem Smotrakov]

Hello,

Please review a couple of new tests that check that:
- Kerberos client tries slave KDC if master KDC is not responding
- if refreshKrb5Config is set to true for Krb5LoginModule, then 
configuration will be refreshed before login() method is called

KDC.java registers a name service which returns 127.0.0.1 for all hosts. 
The name service was updated to throw UnknownHostException for 
"not.existing.host".

Webrev: http://cr.openjdk.java.net/~asmotrak/8075297/webrev.00/
Bug: https://bugs.openjdk.java.net/browse/JDK-8075297

Artem