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 they do not support null.  However, null values may be exposed by using apply() instead of get.
Add doc for the API in ChainedProperty.
Add tests for ChainMakers.deriveChain()
Rename trait PropertiesTestHelp for usage clarity.
Simplify creating DynamicIntProperty in tests.
Clean up imports.
Clean up doc.
Refactor tests to separate most tests from fixture.
Merge pull request #165 from stujapa/scala-chained-property-bindings

archaius-scala: add Scala bindings for Chained Properties