(RequireUtil) Require util where needed

This isn't right. It should be

```
var SamlStrategy = require('passport-saml').Strategy;
var util = require('util');

var ConfigAPI = require('oae-config');
var Context = require('oae-context').Context;
var log = require('oae-logger').logger('oae-authentication');
var Redis = require('oae-util/lib/redis');
```