Expand on a brief error message
Expand on a brief error message

In this case, the remote server did not supply any information
about the error.  Tell the user this so it doesn't look like
the SDK library is accidentally omitting anything.

Change-Id: I8f4757d2075c7cb4708df7b387f02beb2d4e671d

stackforge/python-openstacksdk,stackforge/python-openstacksdk,dtroyer/python-openstacksdk,openstack/python-openstacksdk,dtroyer/python-openstacksdk,openstack/python-openstacksdk