cp file can work

1. consolidate to filer_pb.FileChunk
2. dir add file, mkdir
3. file flush, write

updates having issue

weed/filer2/filer.go

@@ -8,6 +8,7 @@ import (
 	"path/filepath"
 	"time"
 	"os"
+	"github.com/chrislusf/seaweedfs/weed/pb/filer_pb"
 )
 
 type Filer struct {
@@ -105,8 +106,8 @@ func (f *Filer) CreateEntry(entry *Entry) (error) {
 	return nil
 }
 
-func (f *Filer) AppendFileChunk(p FullPath, c FileChunk) (err error) {
-	return f.store.AppendFileChunk(p, c)
+func (f *Filer) AppendFileChunk(p FullPath, chunks []*filer_pb.FileChunk) (err error) {
+	return f.store.AppendFileChunk(p, chunks)
 }
 
 func (f *Filer) FindEntry(p FullPath) (found bool, entry *Entry, err error) {