Cleanup a few comments.

Change-Id: Ia2e2d6e4e1e0a5d2ab0b8ded551bb8a8949ce84a
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/3911
Reviewed-by: Henry Robinson <henry@cloudera.com>
Tested-by: Daniel Hecht <dhecht@cloudera.com>