Removed duplicate properties hash from AF::Rdf

The properties hash duplicated functionality from NodeConfig. This
strips it out.
Merge pull request #394 from no-reply/feature/dedup-properties

Removed duplicate properties hash from AF::Rdf
Enabled class_name constantization on access

This fixes an issue where, in certian edge cases related to
Rdf::Identifiable, a class_name can be specified and used before the
class is defined.