Updating hadoop-daemon.sh to work as expected when nfs is started as a privileged user.

When NFS is started as a privileged user, this change sets up required environment variables:
HADOOP_PID_DIR = $HADOOP_PRIVILEGED_NFS_PID_DIR
HADOOP_LOG_DIR = $HADOOP_PRIVILEGED_NFS_LOG_DIR
HADOOP_IDENT_STRING = $HADOOP_PRIVILEGED_NFS_USER

Also, along with the above, we also now collect ulimits for the right user.