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/volume_info.go

@@ -0,0 +1,65 @@
+package storage
+
+import (
+	"fmt"
+	"github.com/chrislusf/seaweedfs/weed/operation"
+	"sort"
+)
+
+type VolumeInfo struct {
+	Id               VolumeId
+	Size             uint64
+	ReplicaPlacement *ReplicaPlacement
+	Ttl              *TTL
+	Collection       string
+	Version          Version
+	FileCount        int
+	DeleteCount      int
+	DeletedByteCount uint64
+	ReadOnly         bool
+}
+
+func NewVolumeInfo(m *operation.VolumeInformationMessage) (vi VolumeInfo, err error) {
+	vi = VolumeInfo{
+		Id:               VolumeId(*m.Id),
+		Size:             *m.Size,
+		Collection:       *m.Collection,
+		FileCount:        int(*m.FileCount),
+		DeleteCount:      int(*m.DeleteCount),
+		DeletedByteCount: *m.DeletedByteCount,
+		ReadOnly:         *m.ReadOnly,
+		Version:          Version(*m.Version),
+	}
+	rp, e := NewReplicaPlacementFromByte(byte(*m.ReplicaPlacement))
+	if e != nil {
+		return vi, e
+	}
+	vi.ReplicaPlacement = rp
+	vi.Ttl = LoadTTLFromUint32(*m.Ttl)
+	return vi, nil
+}
+
+func (vi VolumeInfo) String() string {
+	return fmt.Sprintf("Id:%d, Size:%d, ReplicaPlacement:%s, Collection:%s, Version:%v, FileCount:%d, DeleteCount:%d, DeletedByteCount:%d, ReadOnly:%v",
+		vi.Id, vi.Size, vi.ReplicaPlacement, vi.Collection, vi.Version, vi.FileCount, vi.DeleteCount, vi.DeletedByteCount, vi.ReadOnly)
+}
+
+/*VolumesInfo sorting*/
+
+type volumeInfos []*VolumeInfo
+
+func (vis volumeInfos) Len() int {
+	return len(vis)
+}
+
+func (vis volumeInfos) Less(i, j int) bool {
+	return vis[i].Id < vis[j].Id
+}
+
+func (vis volumeInfos) Swap(i, j int) {
+	vis[i], vis[j] = vis[j], vis[i]
+}
+
+func sortVolumeInfos(vis volumeInfos) {
+	sort.Sort(vis)
+}