XD-2123 Support for kerberized hdfs

- Modify hdfs.xml and hdfs-dataset.xml to read values
  via from hadoop.properties via property placeholder.
  This is needed for security config to kick in because
  reading properties properties-location in hadoop namespace
  is not enough. Default values for these are empty which
  gets normal hadoop configuration.
- Added same tweaks to shell's shdp namespace usage and
  added empty hadoop.properties file.
- Kerberized config is then enabled i.e. using below
  propertys in hadoop.properties:
  hadoop.security.authorization=true
  hadoop.security.authentication=kerberos
  dfs.namenode.kerberos.principal=hdfs/neo@LOCALDOMAIN
  yarn.resourcemanager.principal=yarn/neo@LOCALDOMAIN
  spring.hadoop.userKeytab=/usr/local/hadoops/janne.keytab
  spring.hadoop.userPrincipal=janne/neo
- Use of userKeytab and userPrincipal enables
  automatic login using kerberos keytab file.