add GDrive provider support (#118)

* GDrive provider support
* More reliable basedir ownership
* Fix mimetype

vendor/cloud.google.com/go/spanner/util_test.go

@@ -0,0 +1,28 @@
+/*
+Copyright 2017 Google LLC
+
+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 spanner
+
+import (
+	"cloud.google.com/go/internal/testutil"
+	"github.com/google/go-cmp/cmp"
+)
+
+func testEqual(a, b interface{}) bool {
+	return testutil.Equal(a, b,
+		cmp.AllowUnexported(TimestampBound{}, Error{}, Mutation{}, Row{},
+			Partition{}, BatchReadOnlyTransactionID{}))
+}