Merge pull request #10 from cpenner461/master

Add kinit requirement to activate_namenode
Add principal and keytab for stackdio user
Merge branch 'master' of github.com:stackdio-formulas/cdh5-formula
Add mapred user to standby namenode so HDFS permissions will work for job history; update landing page with standby namenode; bump a few defaults in the SPECFILE