fixed misc:rewrite use of callbacks for tuple args

For {a, b, c} it used to call for {a, b, c} (ok) then [b, c], then [c]
which is not ok. Now it's strictly, tuple, then if tuple call returns
'continue', it'll pass elements of tuple to callback in turn and
nothing else.

Change-Id: Icf12445a72b1f40311e36f5a4ad3dfbd07455d56
Reviewed-on: http://review.couchbase.org/42222
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>