TST: add connection refused (111) error to skipping for network. the urlerror apparentely

     doesn't provide an errno so were not ignoring this

Author: jreback

pandas/util/testing.py

@@ -1600,7 +1600,8 @@ def dec(f):
     'HTTP Error 403',
     'Temporary failure in name resolution',
     'Name or service not known',
-    )
+    'Connection refused',
+)
 
 # or this e.errno/e.reason.errno
 _network_errno_vals = (