Support bucket versioning (#9377)

- Implement a new xl.json 2.0.0 format to support,
  this moves the entire marshaling logic to POSIX
  layer, top layer always consumes a common FileInfo
  construct which simplifies the metadata reads.
- Implement list object versions
- Migrate to siphash from crchash for new deployments
  for object placements.

Fixes #2111

cmd/os-readdir_test.go

@@ -68,7 +68,7 @@ type result struct {
 
 func mustSetupDir(t *testing.T) string {
 	// Create unique test directory.
-	dir, err := ioutil.TempDir(globalTestTmpDir, "minio-posix-list-dir")
+	dir, err := ioutil.TempDir(globalTestTmpDir, "minio-list-dir")
 	if err != nil {
 		t.Fatalf("Unable to setup directory, %s", err)
 	}