Remove unused HTTPError, will need to use in order to trap error from…

… bs4

stoqs/loaders/SampleLoaders.py

@@ -34,7 +34,7 @@
 from pydap.model import BaseType, DatasetType
 import argparse
 import csv
-from urllib.request import urlopen, HTTPError
+from urllib.request import urlopen
 import requests
 import logging
 from glob import glob