Update README.md

Removed reference to deprecated kraken-puppet repository.
CentOS 6 support
CentOS 6 support
CentOS 6 support
CentOS 6 support
fix in documentation
CentOS 6 support
Zookeeper workaround
Zookeeper workaround
Zookeeper workaround
Zookeeper workaround
Zookeeper workaround
Zookeeper workaround
Zookeeper workaround
Zookeeper workaround
CentOS 6 support
Merge branch 'centos'
Merge pull request #2 from nathan-gs/centos

Centos 6 support
Merge branch 'master' of https://github.com/wikimedia/puppet-cdh4
Zookeeper workaround: changed hostname to fqdn (more accurate)