directory structure change to work with glide

glide has its own requirements. My previous workaround caused me some
code checkin errors. Need to fix this.

weed/storage/file_id.go

@@ -0,0 +1,43 @@
+package storage
+
+import (
+	"encoding/hex"
+	"errors"
+	"strings"
+
+	"github.com/chrislusf/seaweedfs/weed/glog"
+	"github.com/chrislusf/seaweedfs/weed/util"
+)
+
+type FileId struct {
+	VolumeId VolumeId
+	Key      uint64
+	Hashcode uint32
+}
+
+func NewFileIdFromNeedle(VolumeId VolumeId, n *Needle) *FileId {
+	return &FileId{VolumeId: VolumeId, Key: n.Id, Hashcode: n.Cookie}
+}
+func NewFileId(VolumeId VolumeId, Key uint64, Hashcode uint32) *FileId {
+	return &FileId{VolumeId: VolumeId, Key: Key, Hashcode: Hashcode}
+}
+func ParseFileId(fid string) (*FileId, error) {
+	a := strings.Split(fid, ",")
+	if len(a) != 2 {
+		glog.V(1).Infoln("Invalid fid ", fid, ", split length ", len(a))
+		return nil, errors.New("Invalid fid " + fid)
+	}
+	vid_string, key_hash_string := a[0], a[1]
+	volumeId, _ := NewVolumeId(vid_string)
+	key, hash, e := ParseKeyHash(key_hash_string)
+	return &FileId{VolumeId: volumeId, Key: key, Hashcode: hash}, e
+}
+func (n *FileId) String() string {
+	bytes := make([]byte, 12)
+	util.Uint64toBytes(bytes[0:8], n.Key)
+	util.Uint32toBytes(bytes[8:12], n.Hashcode)
+	nonzero_index := 0
+	for ; bytes[nonzero_index] == 0; nonzero_index++ {
+	}
+	return n.VolumeId.String() + "," + hex.EncodeToString(bytes[nonzero_index:])
+}