Add infraenv, setup creds and tee for Kitchen.

go/src/infra/libs/infraenv/paths_posix.go

Index: go/src/infra/libs/infraenv/paths_posix.go
diff --git a/go/src/infra/libs/infraenv/paths_posix.go b/go/src/infra/libs/infraenv/paths_posix.go
new file mode 100644
index 0000000000000000000000000000000000000000..5b07473a657a3d67f1f819a1926e4ef1d3aa015c
--- /dev/null
+++ b/go/src/infra/libs/infraenv/paths_posix.go
@@ -0,0 +1,16 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// +build darwin linux
+
+package infraenv
+
+var (
+	// Paths on the system where credentials are stored.
+	//
+	// This path is provisioned by Puppet.
+	systemCredentialDirs = []string{
+		"/creds/service_accounts",
+	}
+)