Move HostUtil to pkg/volume/util/hostutil

This patch moves the HostUtil functionality from the util/mount package
to the volume/util/hostutil package.

All `*NewHostUtil*` calls are changed to return concrete types instead
of interfaces.

All callers are changed to use the `*NewHostUtil*` methods instead of
directly instantiating the concrete types.

pkg/volume/util/hostutil/hostutil_windows_test.go

@@ -0,0 +1,74 @@
+// +build windows
+
+/*
+Copyright 2017 The Kubernetes Authors.
+
+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 hostutil
+
+import (
+	"io/ioutil"
+	"os"
+	"testing"
+)
+
+func TestGetFileType(t *testing.T) {
+	hu := NewHostUtil()
+
+	testCase := []struct {
+		name         string
+		expectedType FileType
+		setUp        func() (string, string, error)
+	}{
+		{
+			"Directory Test",
+			FileTypeDirectory,
+			func() (string, string, error) {
+				tempDir, err := ioutil.TempDir("", "test-get-filetype-")
+				return tempDir, tempDir, err
+			},
+		},
+		{
+			"File Test",
+			FileTypeFile,
+			func() (string, string, error) {
+				tempFile, err := ioutil.TempFile("", "test-get-filetype")
+				if err != nil {
+					return "", "", err
+				}
+				tempFile.Close()
+				return tempFile.Name(), tempFile.Name(), nil
+			},
+		},
+	}
+
+	for idx, tc := range testCase {
+		path, cleanUpPath, err := tc.setUp()
+		if err != nil {
+			t.Fatalf("[%d-%s] unexpected error : %v", idx, tc.name, err)
+		}
+		if len(cleanUpPath) > 0 {
+			defer os.RemoveAll(cleanUpPath)
+		}
+
+		fileType, err := hu.GetFileType(path)
+		if err != nil {
+			t.Fatalf("[%d-%s] unexpected error : %v", idx, tc.name, err)
+		}
+		if fileType != tc.expectedType {
+			t.Fatalf("[%d-%s] expected %s, but got %s", idx, tc.name, tc.expectedType, fileType)
+		}
+	}
+}