Added missing permissions required for authenticating with Kerberos to HDFS. Also implemented
code to support authentication in the form of using a Kerberos keytab file. In order to support
HDFS authentication, users must install a Kerberos keytab file on each node and transfer it to the
configuration directory. When a user specifies a Kerberos principal in the repository settings the
plugin automatically enables security for Hadoop and begins the login process. There will be a
separate PR and commit for the testing infrastructure to support these changes.