cleanup: Remove definitions and move them to its relative places accordingly

- Move fs-definitions.go and break them into fs-datatypes.go, fs-bucket-acl.go
  and fs-utils.go
- Move api-definitions.go to api-response.go, where they should be.
- Move web-definitions to its related handlers.

pkg/fs/fs-backend-metadata.go

@@ -0,0 +1,89 @@
+/*
+ * Minio Cloud Storage, (C) 2015, 2016 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 fs
+
+import (
+	"github.com/minio/minio/pkg/probe"
+	"github.com/minio/minio/pkg/quick"
+)
+
+var multipartsMetadataPath, bucketsMetadataPath string
+
+// setFSBucketsMetadataPath - set fs buckets metadata path.
+func setFSBucketsMetadataPath(metadataPath string) {
+	bucketsMetadataPath = metadataPath
+}
+
+// SetFSMultipartsMetadataPath - set custom multiparts session
+// metadata path.
+func setFSMultipartsMetadataPath(metadataPath string) {
+	multipartsMetadataPath = metadataPath
+}
+
+// saveMultipartsSession - save multiparts
+func saveMultipartsSession(multiparts Multiparts) *probe.Error {
+	qc, err := quick.New(multiparts)
+	if err != nil {
+		return err.Trace()
+	}
+	if err := qc.Save(multipartsMetadataPath); err != nil {
+		return err.Trace()
+	}
+	return nil
+}
+
+// saveBucketsMetadata - save metadata of all buckets
+func saveBucketsMetadata(buckets Buckets) *probe.Error {
+	qc, err := quick.New(buckets)
+	if err != nil {
+		return err.Trace()
+	}
+	if err := qc.Save(bucketsMetadataPath); err != nil {
+		return err.Trace()
+	}
+	return nil
+}
+
+// loadMultipartsSession load multipart session file
+func loadMultipartsSession() (*Multiparts, *probe.Error) {
+	multiparts := &Multiparts{}
+	multiparts.Version = "1"
+	multiparts.ActiveSession = make(map[string]*MultipartSession)
+	qc, err := quick.New(multiparts)
+	if err != nil {
+		return nil, err.Trace()
+	}
+	if err := qc.Load(multipartsMetadataPath); err != nil {
+		return nil, err.Trace()
+	}
+	return qc.Data().(*Multiparts), nil
+}
+
+// loadBucketsMetadata load buckets metadata file
+func loadBucketsMetadata() (*Buckets, *probe.Error) {
+	buckets := &Buckets{}
+	buckets.Version = "1"
+	buckets.Metadata = make(map[string]*BucketMetadata)
+	qc, err := quick.New(buckets)
+	if err != nil {
+		return nil, err.Trace()
+	}
+	if err := qc.Load(bucketsMetadataPath); err != nil {
+		return nil, err.Trace()
+	}
+	return qc.Data().(*Buckets), nil
+}