archaius-scala: add Scala bindings for Chained Properties

Add Scala bindings for Chained Properties.
Core functionality provided by the ChainedProperty trait; concrete types bind types and provide any extended functionality.
Contrary to the Java underpinnings, by default the Scala bindings do not support null.  However, null values may be exposed by using apply() instead of get.  The only exception presently is ChainedStringProperty.