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_super_block_test.go

@@ -0,0 +1,23 @@
+package storage
+
+import (
+	"testing"
+)
+
+func TestSuperBlockReadWrite(t *testing.T) {
+	rp, _ := NewReplicaPlacementFromByte(byte(001))
+	ttl, _ := ReadTTL("15d")
+	s := &SuperBlock{
+		version:          CurrentVersion,
+		ReplicaPlacement: rp,
+		Ttl:              ttl,
+	}
+
+	bytes := s.Bytes()
+
+	if !(bytes[2] == 15 && bytes[3] == Day) {
+		println("byte[2]:", bytes[2], "byte[3]:", bytes[3])
+		t.Fail()
+	}
+
+}