Add a domain_realm parameter to kerberos::client class
If the user does not provide a domain_realm hash, then use '.realm = REALM' as a default.  Domain is generated by lowercasing the realm and prepending a '.'.
Also allow the logfile for the kdc and admin server to be specified in krb5.conf.
Merge pull request #1 from greg-1-anderson/domain_realm

Add logging and domain_realm parameters to kerberos::client class