#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...