Update SecurityUtil.php

Ensure that uid is always an integer: 


Q	A
Bug fix?	no
New feature?	yes
BC breaks?	no
Deprecations?	no
Tests pass?	yes
Fixed tickets	
License	MIT
Doc PR	no
Javascript class names fixed, refs #724.
Handle checkboxes by z-form-error, closes #636
Merge pull request #856 from rgasch/patch-12

Update SecurityUtil.php
Merge pull request #869 from cmfcmf/checkbox-fix

Handle checkboxes by z-form-error, closes #636
Fixed wrong ORM mapping, closes #822.
Merge pull request #870 from cmfcmf/patch

Fixed wrong ORM mapping, closes #822.
Fixed override path and reviewed all theme overrides, closes #805.
Merge pull request #872 from cmfcmf/override-fix

Fixed override path and reviewed all theme overrides, closes #805.
Fixed password recovery process when using your email adress. $uname thab only is available using the $userObj, closes #750.
Merge pull request #871 from cmfcmf/pw-recovery

Fixed password recovery process when using your email adress. $uname that only is available using the $userObj, closes #750.
Fixed wrong return statement, closes #756.
Merge pull request #874 from cmfcmf/categories-fix

Fixed wrong return statement, closes #756.
Wrong output by user deletion fixed, closes #866.
Merge pull request #868 from phaidon/javascript-class-names-fix

Javascript class names fixed, refs #724.
Merge pull request #875 from phaidon/delete-user-fix

Wrong output by user deletion fixed, closes #866.
System::queryStringSetVar fixed, closes #753.
Add GeneratorBundle as a dependency.
Fixed typo.
Merge pull request #877 from cmfcmf/typo

Fixed typo.