CHANGE-709 - Refactor logging infrastructure (continuation)

CHANGE-709 - Refactor logging infrastructure (continuation from earlier changes)
- fix chicken/egg problem with log initialization
- add explicit logging messages in more places
- relocate log-delete code to logwriter
<a href='#crh-start'></a><a href='#crh-data-
Hmm... are you not familiar with the concept of a local variable?  How would this break functionality:
```php
public function __construct(notifier $aNotifier = null) {
    $this->notifier = $aNotifier ?: new notifier;
}
```