Gradle Release Plugin - pre tag commit:  'archaius-0.5.15'.
Gradle Release Plugin - new version commit:  'archaius-0.5.16-SNAPSHOT'.
#51. Provide mechanism for Dynamic Property users to un-subscribe callbacks for property value changes. This will free the references by the static DP so GC can reclaim those property wrapper instances in time.
#51. Provide mechanism for Dynamic Property users to un-subscribe callbacks for property value changes. This will free the references by the static DP so GC can reclaim those property wrapper instances in time.

Addressed review comments.
Merge pull request #159 from howardyuan/master

#51. Provide mechanism for Dynamic Property users to un-subscribe callba...
#160. ChainedDynamicProperty.BooleanProperty requires DynamicBooleanPropertyThatSupportsNull. But there's no public constructor for that class. Open the constructor to be "public".
#160, #162. ChainedDynamicProperty.BooleanProperty requires DynamicBooleanPropertyThatSupportsNull. But there's no public constructor for that class. Open the constructor to be "public".

Add LongProperty
Merge pull request #161 from howardyuan/master

#160. ChainedDynamicProperty.BooleanProperty requires DynamicBooleanProp...
Gradle Release Plugin - pre tag commit:  'archaius-0.5.16'.
Gradle Release Plugin - new version commit:  'archaius-0.5.17-SNAPSHOT'.
#163. Change the callback list to a list of WeakReference so DynamicPropertyWrapper objects can be GCed in time.
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.
#163. Change the callback list to a list of WeakReference so DynamicPropertyWrapper objects can be GCed in time. Add unit test to confirm that weak reference works as designed.