verify_measure need not know about primitive measures
verify_measure need not know about primitive measures

Rely on the scalar verification (such as verify/normal or verify/simplify) to recur into constructors such as Gaussian

Obviates https://github.com/hakaru-dev/hakaru/commit/744b86ad3d148f1580f899ab0d28d41e654cd9fe#commitcomment-16970145

zachsully/hakaru,zachsully/hakaru,zaxtax/hakaru,zaxtax/hakaru