- Remove global variables for maintaining the Txnid
- do not print out the stack in Close()/Terminate() methods unless for debug

Change-Id: I774aa44496d56e1a7900f08a7e85433db6588776
Reviewed-on: http://review.couchbase.org/41724
Reviewed-by: John Liang <johliang00@gmail.com>
Tested-by: John Liang <johliang00@gmail.com>