CBQE-927: add offline upgrade with flags test

Change-Id: If0b1d3340f7a4ffc365c0b265aee48f811847227
Reviewed-on: http://review.couchbase.org/27131
Reviewed-by: Iryna Mironava <irynamironava@yandex.ru>
Tested-by: Iryna Mironava <irynamironava@yandex.ru>