'Find a folder on the SC using the specified url.
Most of the time the folder will already have been created so
we look for the end folder and check that the rest of the path is
right.
The REST url sent in defines the folder type being created on the Dell
Storage Center backend.  Thus this is generic to server and volume
folders.
:param url: The portion of the url after the base url (see http class)
to use for this operation.  (Can be for Server or Volume
folders.)
:param foldername: Full path to the folder we are looking for.
:returns: Dell folder object.'

def _find_folder(self, url, foldername, ssn=(-1)):

    ssn = self._vet_ssn(ssn)
    pf = self._get_payload_filter()
    pf.append('scSerialNumber', ssn)
    basename = os.path.basename(foldername)
    pf.append('Name', basename)
    folderpath = os.path.dirname(foldername)
    if (folderpath != ''):
        folderpath += '/'
        pf.append('folderPath', folderpath)
    folder = None
    r = self.client.post(url, pf.payload)
    if self._check_result(r):
        folder = self._get_result(r, 'folderPath', folderpath)
    return folder
