add default writer for glog to be integrated with other package; comments update for glog

geg/os/gcron/gcron2.go

@@ -1,7 +1,7 @@
 package main
 
 import (
-	"fmt"
+	"github.com/gogf/gf/g"
 	"github.com/gogf/gf/g/os/gcron"
 	"time"
 )
@@ -12,7 +12,9 @@ func test() {
 
 func main() {
 	_, err := gcron.Add("*/10 * * * * ?", test)
-	fmt.Println(err)
-	fmt.Println(gcron.Entries())
+	if err != nil {
+		panic(err)
+	}
+	g.Dump(gcron.Entries())
 	time.Sleep(10 * time.Second)
 }

geg/os/glog/glog_writer.go

@@ -0,0 +1,10 @@
+package main
+
+import (
+	"github.com/gogf/gf/g/os/glog"
+)
+
+func main() {
+	w := glog.GetWriter()
+	w.Write([]byte("hello"))
+}