test: crypto createClass instanceof Class

The crypto classes are also exposed as createClass for each class. This
tests that each of them returns an instance of the class in question.

PR-URL: https://github.com/nodejs/node/pull/8188


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>