Introduce some default log verbosity control

Move a lot of common error logging into better buckets:

glog.Errorf() - Always an error
glog.Warningf() - Something unexpected, but probably not an error
glog.V(0) - Generally useful for this to ALWAYS be visible
            to an operator
            * Programmer errors
            * Logging extra info about a panic
            * CLI argument handling
glog.V(1) - A reasonable default log level if you don't want
            verbosity
            * Information about config (listening on X, watching Y)
            * Errors that repeat frequently that relate to conditions
              that can be corrected (pod detected as unhealthy)
glog.V(2) - Useful steady state information about the service
            * Logging HTTP requests and their exit code
            * System state changing (killing pod)
            * Controller state change events (starting pods)
            * Scheduler log messages
glog.V(3) - Extended information about changes
            * More info about system state changes
glog.V(4) - Debug level verbosity (for now)
            * Logging in particularly thorny parts of code where
              you may want to come back later and check it

pkg/kubelet/dockertools/docker.go

@@ -75,11 +75,11 @@ func NewDockerPuller(client DockerInterface) DockerPuller {
 	if err == nil {
 		cfg.addToKeyring(dp.keyring)
 	} else {
-		glog.Errorf("Unable to parse docker config file: %v", err)
+		glog.Errorf("Unable to parse Docker config file: %v", err)
 	}
 
 	if dp.keyring.count() == 0 {
-		glog.Infof("Continuing with empty docker keyring")
+		glog.V(1).Infof("Continuing with empty Docker keyring")
 	}
 
 	return dp
@@ -348,7 +348,7 @@ func ParseDockerName(name string) (podFullName, uuid, containerName string, hash
 			var err error
 			hash, err = strconv.ParseUint(pieces[1], 16, 32)
 			if err != nil {
-				glog.Infof("invalid container hash: %s", pieces[1])
+				glog.Warningf("invalid container hash: %s", pieces[1])
 			}
 		}
 	}