sandbox: add app.yaml to serve with Managed VMs

Change-Id: I912fe78c065efe442d2b72ac930ab9e36dac3210
Reviewed-on: https://go-review.googlesource.com/2703
Reviewed-by: Johan Euphrosine <proppy@google.com>
Reviewed-by: Andrew Gerrand <adg@golang.org>
diff --git a/sandbox/app.yaml b/sandbox/app.yaml
new file mode 100644
index 0000000..68c970c
--- /dev/null
+++ b/sandbox/app.yaml
@@ -0,0 +1,12 @@
+application: golang-org
+version: sandbox
+runtime: custom
+api_version: go1
+vm: true
+
+manual_scaling:
+  instances: 15
+
+handlers:
+- url: /.*
+  script: _go_app