Switch to glog for logging, bridge logging to glog.

1) imported glog to third_party (previous commit)
2) add support for third_party/update.sh to update just one pkg
3) search-and-replace:
  s/log.Printf/glog.Infof/
  s/log.Print/glog.Info/
  s/log.Fatalf/glog.Fatalf/
  s/log.Fatal/glog.Fatal/
4) convert glog.Info.*, err into glog.Error*

Adds some util interfaces to logging and calls them from each cmd, which
will set the default log output to write to glog.  Pass glog-wrapped
Loggers to etcd for logging.

Log files will go to /tmp - we should probably follow this up with a
default log dir for each cmd.

The glog lib is sort of weak in that it only flushes every 30 seconds, so
we spin up our own flushing goroutine.

pkg/apiserver/logger.go

@@ -18,10 +18,11 @@ package apiserver
 
 import (
 	"fmt"
-	"log"
 	"net/http"
 	"runtime"
 	"time"
+
+	"github.com/golang/glog"
 )
 
 // Add a layer on top of ResponseWriter, so we can track latency and error
@@ -56,7 +57,7 @@ func (rl *respLogger) Addf(format string, data ...interface{}) {
 // Log is intended to be called once at the end of your request handler, via defer
 func (rl *respLogger) Log() {
 	latency := time.Since(rl.startTime)
-	log.Printf("%s %s: (%v) %v%v%v", rl.req.Method, rl.req.RequestURI, latency, rl.status, rl.statusStack, rl.addedInfo)
+	glog.Infof("%s %s: (%v) %v%v%v", rl.req.Method, rl.req.RequestURI, latency, rl.status, rl.statusStack, rl.addedInfo)
 }
 
 // Implement http.ResponseWriter