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/erasure-errors.go

@@ -0,0 +1,28 @@
+/*
+ * MinIO Cloud Storage, (C) 2016, 2018 MinIO, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package cmd
+
+import "errors"
+
+// errErasureReadQuorum - did not meet read quorum.
+var errErasureReadQuorum = errors.New("Read failed. Insufficient number of disks online")
+
+// errErasureWriteQuorum - did not meet write quorum.
+var errErasureWriteQuorum = errors.New("Write failed. Insufficient number of disks online")
+
+// errNoHealRequired - returned when healing is attempted on a previously healed disks.
+var errNoHealRequired = errors.New("No healing is required")