allow user to specify custom render handler

app.use(stormpath.init(app, {
...
    renderHandler: function(view,res,options) {
      // custom render handling here - use jade, handlebars etc or just set some extra form options
    },
...
}

adding this option allows the developer to use their own view engine (jade / handlebars etc) when rendering any of the stormpath views. It also allows the developer to add / remove options before the view is rendered