Log info on failure to connect

When multiple servers are avilable we were simply suppressing information on
why a connection failed.
Log it as 'info' so that it is possible to diagnose issues more easily.

ipalib/rpc.py

@@ -665,6 +665,8 @@ class xmlclient(Connectible):
             except Exception, e:
                 if not fallback:
                     raise
+                else:
+                    self.log.info('Connection to %s failed with %s', url, e)
                 serverproxy = None
 
         if serverproxy is None: