fixes #569 apt module problems on old versions of apt-python (namely debian 5.0)

library/apt

@@ -163,11 +163,11 @@ cache = apt.Cache()
 if default_release:
     apt_pkg.config['APT::Default-Release'] = default_release
     # reopen cache w/ modified config
-    cache.open()
+    cache.open(progress=None)
 
 if update_cache == 'yes':
     cache.update()
-    cache.open()
+    cache.open(progress=None)
     if package == None:
         exit_json(changed=False)