CBQE-0: add cb_2.1.0_upgrade.iss

and revert Ie4932023790fc830a8174e847255d825e5f90791

Change-Id: I7c633cd601a2c00b61e4feacbf4bdfda011e11ce
Reviewed-on: http://review.couchbase.org/26831
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Andrei Baranouski <andrei.baranouski@gmail.com>