Infer better document titles

Right now, we simply use the URI base name to determine the PDF filename:
```
let filePath = path.basename(url) + '.pdf';
```
It would be best to derive the output filename from the document title.  This is because Jire will create paths for documents like:
```
https://wiki.mydomain.com/pages/viewpage.action?pageId=143297573
```

