Updated dependencies

All dependencies updated to their latest versions. Validator.js has changed its major version, so there was a bit of work to get it working. All default error messages have been removed, and a couple of methods have changed name / been removed. I have kept backwards compat for removed methods by using the `extend` functionality, and the old code from validator v.1.5.1.

Default error messages are gone, but I think thats a very minor change we can allow into 1.7