CBQE-2404 replace sort.exe -u that does not work on windows
with sorted(set()) in python

Change-Id: I4f9662e42d4038c59643793cf079c12ba6b47720
Reviewed-on: http://review.couchbase.org/41214
Reviewed-by: Thuan Nguyen <soccon@gmail.com>
Tested-by: Thuan Nguyen <soccon@gmail.com>