Add initial support for bucket lifecycle (#7563)

This PR is based off @sinhaashish's PR for object lifecycle
management, which includes support only for,
- Expiration of object
- Filter using object prefix (_not_ object tags)

N B the code for actual expiration of objects will be included in a
subsequent PR.

pkg/lifecycle/and.go

@@ -0,0 +1,42 @@
+/*
+ * MinIO Cloud Storage, (C) 2019 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 lifecycle
+
+import (
+	"encoding/xml"
+	"errors"
+)
+
+// And - a tag to combine a prefix and multiple tags for lifecycle configuration rule.
+type And struct {
+	XMLName xml.Name `xml:"And"`
+	Prefix  string   `xml:"Prefix,omitempty"`
+	Tags    []Tag    `xml:"Tag,omitempty"`
+}
+
+var errAndUnsupported = errors.New("Specifying <And></And> tag is not supported")
+
+// UnmarshalXML is extended to indicate lack of support for And xml
+// tag in object lifecycle configuration
+func (a And) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
+	return errAndUnsupported
+}
+
+// MarshalXML is extended to leave out <And></And> tags
+func (a And) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
+	return nil
+}