Add request to get properties of a PDF file

Pretty much the same as the other two except
that it takes an additional parameter to specify
what info to retrieve.
@datalogics-bhaugen yeah, the other two use an objects array as well
```
// create a new objects array to pass the info we need to down to the BasicRequest class
        objects = new Object[] {BasicRequest.WEB_API_URL + REQUEST_PATH, entity};
```