CBQE-1551: add base64 test for tuq

Change-Id: Ib7748c15db28fa58ffb9218843ac2f4efed960e8
Reviewed-on: http://review.couchbase.org/29712
Reviewed-by: Iryna Mironava <irynamironava@yandex.ru>
Tested-by: Iryna Mironava <irynamironava@yandex.ru>