Changes to allow the tool to be deployed to App Engine Managed VMs.

This consists of:
1. Making the gce.sh file reusable for Docker images
2. Adding a Dockerfile
3. Adding an app.yaml fil.
4. Adding a handler for the health check requests at "/_ah/health"
Changed script and css links to use https instead of http. This is required in order to server the UI over https
Fixed a bug in the App Engine deployment where we never started cron, causing the TODOs to never get refreshed
Merge pull request #2 from google/ojarjur-dev

Enable deploying to Google App Engine Managed VMs