Feature/add express validator

[Bigghead]

Tested portfolio routes. The reason it wasn't working as expected previously was because I had written it as a middleware function (req, res, next) => ......next(), but it expects that middleware to be in an array format for some reason:

router.post('/portfolios', [ sanitize('name') ], (req, res) => {.....}

Rewrote the reusable sanitization/validation( for later ) middleware to return an array