ASACORE-1012 Allow cleanup of IpNameService singleton

We'd like to be able to cleanly unload AJ code from Windows (service)
process. Currently IpNameService singleton holds Winsock resources via a
call to WSAStartup. In order to properly unload all resources, we also need to
call WSACleanup after IpNameService goes away. This effectively calls for
a new static cleanup method to destroy the singleton (which must be the last
call to name service).

Change-Id: I85b14eeddbb670bc2d3abc9a178f0ec6142c8814
Signed-off-by: Way Vadhanasin <wayvad@microsoft.com>
Merge "ASACORE-1012 Allow cleanup of IpNameService singleton"