Report name resolution errors properly

Errors in name resolution have been logged previously with the url path
rather than the hostname. That resulted in incorrect errors like:

InvalidEndpoint: Error finding address for
/v1/images/detail?is_public=none&limit=20: [Errno -2]
Name or service not known

rather than one mentioning hostname itself. This patch changes the log
message to fit the situation.

Change-Id: I1eecbcb22d41b1341c214937b9cbfd046fd301a0
Merge "Report name resolution errors properly"