Upgrade to Hiera 5

[bschonec]

There's a lot of redundant data in the params.pp file that could/should be migrated to the Hiera 5 methodology here.

Also, RHEL5 (perhaps RHEL6) should be deprecated along with Centos versions to be determined.

Comments?

[bschonec]

This would be solved by #282.

[saz]

#282 wasn't really solving this. A proper PR would be great. I won't promise that I've got time before the next release to work on this :-)