[node:list] non-wildcard invalid path should show an error

```
PHPCRSH> node:list /this/path/does/not/exist
0 nodes in set
```

Should display an error indicating that the requested node does not exist.

At the moment as the node does not exist it assumes that it is a wildcard.

We need to detect if the path is a wildcard or not before deciding how to retrieve the requested node.
