Add automatic scaling for app.yaml

Author: addyosmani

app.yaml

@@ -7,4 +7,7 @@ handlers:
   script: IGNORED
   secure: always
 skip_files:
-  - ^(.*/)?.*/node_modules/.*$
+  - ^(.*/)?.*/node_modules/.*$
+automatic_scaling:
+  min_num_instances: 15
+  max_num_instances: 100