aetest: remove `vm: true` from app.yaml template (#80)

diff --git a/aetest/instance_vm.go b/aetest/instance_vm.go
index 70d4eec..f9c18d3 100644
--- a/aetest/instance_vm.go
+++ b/aetest/instance_vm.go
@@ -269,7 +269,6 @@
 version: 1
 runtime: go
 api_version: go1
-vm: true
 
 handlers:
 - url: /.*