3.0 split utility

This set of changes make Utility completely independent of the rest of CakePHP. It introduces one change that needs to be reflected in the app template as `Configure` is no longer used inside this namespace.

Applications will need to add this to the bootstrap:

```php
Security::salt(Configure::read('Security.salt'));
```
Probably with adding those as requirements is composer won't install CakePHP if they aren't installed. Given that XML isn't coupled into core classes if someone doesn't need to deal with XML at all in his project, he would be unnecessarily prevented from installing and using CakePHP.