Add a basic Mojo app that initializes V8

mojo/apps/js/v8_environment.h

Index: mojo/apps/js/v8_environment.h
diff --git a/apps/switches.cc b/mojo/apps/js/v8_environment.h
similarity index 54%
copy from apps/switches.cc
copy to mojo/apps/js/v8_environment.h
index 60f94175f67827ed2e4b08d87be6a9b2c3a4122e..88d1963646f4e73c13a7c99046c4eb53385f96f4 100644
--- a/apps/switches.cc
+++ b/mojo/apps/js/v8_environment.h
@@ -2,11 +2,15 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "apps/switches.h"
+#ifndef MOJO_APPS_JS_V8_ENVIRONMENT_H_
+#define MOJO_APPS_JS_V8_ENVIRONMENT_H_
 
+namespace mojo {
 namespace apps {
 
-// Loads an app from the specified directory and launches it.
-const char kLoadAndLaunchApp[] = "load-and-launch-app";
+void InitializeV8();
 
 }  // namespace apps
+}  // mojo
+
+#endif  // MOJO_APPS_JS_V8_ENVIRONMENT_H_