Bump version 1.3.9

Change-Id: I48aa1e768258b890f7b30535c05f07e48405a415
Reviewed-on: http://review.couchbase.org/40948
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Tested-by: Sergey Avseyev <sergey.avseyev@gmail.com>