Puppetizing HA NameNode via Quorum Based JournalNode.

Notables:

- cdh4::hadoop interface change: s/namenode_hostname/namenode_hosts/g

- cdh4::hadoop::journalnode class is applied automatically
  based on $journalnode_hosts.

- cdh4::hadoop::namenode::primary is now included by cdh4::hadoop::master.
  In HA mode, the primary class will transition the primary NameNode to active
  after the first formatting.

- cdh4::hadoop::namenode::standby overrides namenode -format
  exec to bootstrap the standby NameNode dfs.name.dir

- Base HDFS directory creation has been moved out of
  cdh4::hadoop::namenode and into cdh4::hadoop::namenode::primary since
  cdh4::hadoop::namenode might now be applied on more than
  one node.

Change-Id: I78b1e51a5d027a6f48b8392b2ca0a35b6199a97b