Logging enhancements

Added additional log messages so that it is clearly visible when using `--debug` what is being emitted into the catalog. Examples:

```
Debug: /Stage[main]/Main/Packagelist[/root/list.txt]: ensuring man-pages-overrides => latest
Debug: /Stage[main]/Main/Packagelist[/root/list.txt]: ensuring libgssglue => purged
```

This change also makes use of the Puppet instance methods for logging and failing. This injects the resource name into the log message automatically for more clarity.