adds environment variable for analytics tracking (GoogleCloudPlatform#277)

Author: bshaffer

appengine/flexible/analytics/app.yaml

@@ -1,5 +1,6 @@
 runtime: php
 env: flex
 
-runtime_config:
-  document_root: web
+env_variables:
+  GA_TRACKING_ID: "YOUR-GA-TRACKING-ID"
+

appengine/flexible/analytics/web/index.php renamed to appengine/flexible/analytics/index.php

@@ -17,9 +17,9 @@
 
 // Install composer dependencies with "composer install"
 // @see http://getcomposer.org for more information.
-require __DIR__ . '/../vendor/autoload.php';
+require __DIR__ . '/vendor/autoload.php';
 
-$app = require __DIR__ . '/../app.php';
+$app = require __DIR__ . '/app.php';
 
 // Run the app!
 // use "gcloud app deploy"