Add class to install and configure the Route53 DNS plugin for OpenShift

This change adds a puppet class to install and configure the Route53 DNS plugin for OpenShift.

It adds three variables to the openshift_origin global hash:

* ::openshift_origin::aws_zoneid - the Route53 zone ID hash string for the dynamic zone
* ::openshift_origin::aws_access_key_id - the user's AWS access key ID for their AWS account
* ::openshift_origin:aws_secret_key - the user's AWS authentication secret for their AWS account