CBQE-1959: tuq: add date-time fns tests

Change-Id: Ib5cafe9d5a01159b5fb08de495fd0c1f21035d0b
Reviewed-on: http://review.couchbase.org/33121
Reviewed-by: Iryna Mironava <irynamironava@yandex.ru>
Tested-by: Iryna Mironava <irynamironava@yandex.ru>