CDH-14830: Use correct service name as a Kerberos client

Clients need to provide the correct service name to Kerberos
servers. This patch plumbs a service name all the way from ThriftClient
and the ClientCache to the AuthProvider.

Change-Id: Iad80833a0a24c5021b209bf6704272222c067b57
Reviewed-on: http://gerrit.ent.cloudera.com:8080/1969
Reviewed-by: Henry Robinson <henry@cloudera.com>
Tested-by: jenkins