Add render() method to be called from controllers

[glensc]

Update each route to return a Response, or update $response. This is the pattern to be used and without magic.

This undoes the middleware for render:

• b696f8e - Add base controller class & update tests. (7 years ago)
• 550482d - Add middleware renderer. (7 years ago)
• ebc69b3 - Convert run controller to use middleware. (7 years ago)
• 8706219 - Move remaining controllers to middleware rendering. (7 years ago)

I believe the original purpose was to able to test controllers behavior, this problem is solved by fetching all() from view:

-        $result = $this->runs->templateVars();
+        $result = $this->view->all();

In fact, this brought up a problem that tests did not even use proper View. Tests used default \Slim\View not \Slim\Views\Twig and that View did not have template extensions present.