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-utils.go

@@ -0,0 +1,55 @@
+/*
+ * 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 (
+	"regexp"
+	"unicode/utf8"
+)
+
+// validBucket regexp.
+var validBucket = regexp.MustCompile(`^[a-z0-9][a-z0-9\.\-]{1,61}[a-z0-9]$`)
+
+// IsValidBucketName - verify bucket name in accordance with
+//  - http://docs.aws.amazon.com/AmazonS3/latest/dev/UsingBucket.html
+func IsValidBucketName(bucket string) bool {
+	if bucket == "" {
+		return false
+	}
+	if len(bucket) < 3 || len(bucket) > 63 {
+		return false
+	}
+	if bucket[0] == '.' || bucket[len(bucket)-1] == '.' {
+		return false
+	}
+	return validBucket.MatchString(bucket)
+}
+
+// IsValidObjectName - verify object name in accordance with
+//   - http://docs.aws.amazon.com/AmazonS3/latest/dev/UsingMetadata.html
+func IsValidObjectName(object string) bool {
+	if object == "" {
+		return true
+	}
+	if len(object) > 1024 || len(object) == 0 {
+		return false
+	}
+	if !utf8.ValidString(object) {
+		return false
+	}
+	return true
+}