Add App Engine Standard app for proxying API requests.

gae-service-proxy is a barebones App Engine app that will forward requests
to App Engine only APIs. This is secure because it does not authorize the
requests it forwards.

Change-Id: I8b248d1a97784ef759dc010f00893ba4748efb0d
Reviewed-on: https://go-review.googlesource.com/38398
Reviewed-by: Tuo Shan <shantuo@google.com>
diff --git a/gae-service-proxy/app.yaml b/gae-service-proxy/app.yaml
new file mode 100644
index 0000000..d01f79e
--- /dev/null
+++ b/gae-service-proxy/app.yaml
@@ -0,0 +1,10 @@
+runtime: go
+api_version: go1
+service: serviceproxy
+
+handlers:
+- url: /.*
+  script: _go_app
+- url: /_ah/remote_api
+  script: _go_app
+
diff --git a/gae-service-proxy/main.go b/gae-service-proxy/main.go
new file mode 100644
index 0000000..5f7a7ed
--- /dev/null
+++ b/gae-service-proxy/main.go
@@ -0,0 +1,3 @@
+package main
+
+import _ "google.golang.org/appengine/remote_api"