fail earlier on API error

Author: Romain Dartigues

session.go

@@ -146,7 +146,9 @@ func (s *Session) init(config *configv3.Config, configUaa *configv3.Config, conf
 	// create an uaa client with cf_username/cf_password or client_id/client secret
 	// to use it for authenticate requests
 	uaaClient := uaa.NewClient(config)
-	uaaClient.GetAPIVersion()
+	if _, err := uaaClient.GetAPIVersion(); err != nil {
+		return fmt.Errorf("unable to get API version: %s", err)
+	}
 
 	uaaAuthWrapper := uaaWrapper.NewUAAAuthentication(nil, configUaa)
 	uaaClient.WrapConnection(uaaAuthWrapper)