Add check to return null BrokeredMessage in ReceiveMessageResult when
retrieving Message on Empty Queue
Add test cases when Retrieving from Empty Queue in both RECEIVE/DELETE
and PEEK/LOCK modes.
Update existing test to be compatible with receiving null
BrokeredMessage instead of uninitialized one.
Merge branch 'dev' of
https://github.com/BillAtPros/azure-sdk-for-java.git into dev

Conflicts:
	microsoft-azure-api/src/main/java/com/microsoft/windowsazure/services/serviceBus/implementation/ServiceBusRestProxy.java