Partitioned Region clear operations can occur during concurrent data operations

Clear operations are successful when concurrent read/write operations occur. Ensure there are test coverage for this use case and modify the code needed to enable this.

Acceptance :

• Passing DUnit tests where clear operations are successful on partitioned region with 
• concurrent puts (writes) and clear op
• concurrent gets (reads) and clear op

• Test coverage to when a member departs in this scenario
• Test coverage to when a member restarts in this scenario
• Unit tests with complete code coverage for the newly written code.